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All questions of Force and Laws of Motion for Grade 9 Exam
Inertia- a)sets objects in motion
- b)causes changes in motion
- c)is the result of a net force
- d)is directly proportional to the mass of an object
Correct answer is option 'D'. Can you explain this answer?
Inertia
a)
sets objects in motion
b)
causes changes in motion
c)
is the result of a net force
d)
is directly proportional to the mass of an object
|
Payal Choudhary answered |
The concept of inertia is a fundamental concept in physics. It is defined as the tendency of an object to resist changes in its state of motion. In other words, it is the property of an object that causes it to remain at rest or in motion with a constant velocity unless acted upon by an external force. The correct option among the given options is option D, which states that inertia is directly proportional to the mass of an object.
Explanation:
Direct Proportionality to Mass:
Inertia is directly proportional to the mass of an object. This means that the greater the mass of an object, the greater its inertia. This can be explained using Newton's first law of motion, which states that an object at rest will remain at rest, and an object in motion will continue in motion with a constant velocity unless acted upon by an external force.
For example, consider a small ball and a large ball. If we push both balls with the same force, the small ball will move faster than the large ball because it has less mass. This is because the large ball has more inertia, and it requires more force to put it in motion.
The Importance of Inertia:
Inertia is an important concept in physics, and it has many practical applications. For example, it is the reason why seat belts are important in cars. When a car suddenly stops, the passengers continue to move forward due to their inertia. The seat belt applies an external force that stops the passengers from moving forward and prevents injuries.
Conclusion:
In conclusion, inertia is the tendency of an object to resist changes in its state of motion. It is directly proportional to the mass of an object. The greater the mass of an object, the greater its inertia. Inertia has many practical applications in everyday life and is a fundamental concept in physics.
Explanation:
Direct Proportionality to Mass:
Inertia is directly proportional to the mass of an object. This means that the greater the mass of an object, the greater its inertia. This can be explained using Newton's first law of motion, which states that an object at rest will remain at rest, and an object in motion will continue in motion with a constant velocity unless acted upon by an external force.
For example, consider a small ball and a large ball. If we push both balls with the same force, the small ball will move faster than the large ball because it has less mass. This is because the large ball has more inertia, and it requires more force to put it in motion.
The Importance of Inertia:
Inertia is an important concept in physics, and it has many practical applications. For example, it is the reason why seat belts are important in cars. When a car suddenly stops, the passengers continue to move forward due to their inertia. The seat belt applies an external force that stops the passengers from moving forward and prevents injuries.
Conclusion:
In conclusion, inertia is the tendency of an object to resist changes in its state of motion. It is directly proportional to the mass of an object. The greater the mass of an object, the greater its inertia. Inertia has many practical applications in everyday life and is a fundamental concept in physics.
Impulse is the other name of- a)inertia
- b)momentum
- c)force
- d)change in momentum
Correct answer is option 'D'. Can you explain this answer?
Impulse is the other name of
a)
inertia
b)
momentum
c)
force
d)
change in momentum
|
|
Dhiraj Sarma answered |
Since momentum depends on impulse
I.e if momentum increase impulse increase vice versa
I.e if momentum increase impulse increase vice versa
The S.I. unit of force is- a)Newton-metre
- b)Newton
- c)Newton per second
- d)Newton per square metre
Correct answer is option 'B'. Can you explain this answer?
The S.I. unit of force is
a)
Newton-metre
b)
Newton
c)
Newton per second
d)
Newton per square metre
|
Prachi Rathore answered |
Yes the si unit of force is newton.
If no external force acts on a moving object:
- a)It will not be affected at all.
- b)It should remain in motion But, it will stop due to Friction
- c)It will stop moving.
- d)It will remain at rest forever.
Correct answer is option 'B'. Can you explain this answer?
If no external force acts on a moving object:
a)
It will not be affected at all.
b)
It should remain in motion But, it will stop due to Friction
c)
It will stop moving.
d)
It will remain at rest forever.
|
Jaitavi answered |
No external force is being applied on that moving object. If no force is applied then it will continue doing it's work. Just like in the question they have asked, it was moving in a straight line, so no external force is applied that's why it is moving in the same sped in a straight line.
Change in momentum when a car weighing 700kg changes its speed from 100m/s to 200 m/s is:- a)14000 kg.m/s
- b)10500000 kg.m/s
- c)21000000 kg.m/s
- d)70000 kg.m/s
Correct answer is option 'D'. Can you explain this answer?
Change in momentum when a car weighing 700kg changes its speed from 100m/s to 200 m/s is:
a)
14000 kg.m/s
b)
10500000 kg.m/s
c)
21000000 kg.m/s
d)
70000 kg.m/s
|
Aditya Shah answered |
Change in momentum = mv - mu
When m = 7000kg, v= 200m/s, u = 100 m/s
Now, 700 * 200 - 700 x 100 = 140000 - 70000 = 70000 kg. m/s
When m = 7000kg, v= 200m/s, u = 100 m/s
Now, 700 * 200 - 700 x 100 = 140000 - 70000 = 70000 kg. m/s
Find the time taken by a body of mass 16 kg to come to rest from a uniform velocity of magnitude 10 m/s, when a force of 4N is applied continously
- a)20 s
- b)30 s
- c)40 s
- d)50 s
Correct answer is option 'C'. Can you explain this answer?
Find the time taken by a body of mass 16 kg to come to rest from a uniform velocity of magnitude 10 m/s, when a force of 4N is applied continously
a)
20 s
b)
30 s
c)
40 s
d)
50 s
|
|
Aditya Shah answered |
To find the time taken for the body to come to rest, we can use the formula derived from Newton's second law:
F=ma
where:
- F is the force applied,
- m is the mass of the body,
- a is the acceleration.
First, we calculate the acceleration:
The body is initially moving with a velocity of 10 m/s and will come to rest, so the final velocity v=0v = 0v=0.
Using the equation of motion:
v=u+at
where:
- v is the final velocity (0 m/s),
- u is the initial velocity (10 m/s),
- a is the acceleration (-0.25 m/s²) (negative because the force is acting opposite to the direction of motion),
- t is the time taken.
Substitute the values:
0=10+(−0.25)t
0.25t=10
So, the time taken by the body to come to rest is 40 seconds.
Answer: 3 (40 s)
If the force acting on the body is zero. Its momentum is:- a)Zero
- b)Constant
- c)Infinite
- d)None of the above
Correct answer is option 'B'. Can you explain this answer?
If the force acting on the body is zero. Its momentum is:
a)
Zero
b)
Constant
c)
Infinite
d)
None of the above
|
Vrinda Maheshwari answered |
yes it will be constant because force acting on both sides equally it will be zero that's why ans is constant... hope it is helpful for you!
A player is catching a ball. Consider the action force to be the impact of the ball against the player’s glove. What is the reaction force?- a)Force that the glove exerts on the ball.
- b)The players grip on the ball.
- c)Friction of the ground.
- d)The muscular effort in the player’s arm.
Correct answer is option 'A'. Can you explain this answer?
A player is catching a ball. Consider the action force to be the impact of the ball against the player’s glove. What is the reaction force?
a)
Force that the glove exerts on the ball.
b)
The players grip on the ball.
c)
Friction of the ground.
d)
The muscular effort in the player’s arm.
|
|
Arjun Sharma answered |
Reaction force: Force that the glove exerts on the ball is the reaction force opposite to the impact of ball on player’s hand.
A person standing on a weighing scale sees a reading on the scale as 148 pounds. This person is acted on by- a)No forces at all.
- b)Two forces of equal magnitude acting in opposite directions.
- c)Only one force of 148 pounds, as shown by the reading on the scale.
- d)Only one force, of 296 pounds (= 2 × 148 pounds)
Correct answer is option 'B'. Can you explain this answer?
A person standing on a weighing scale sees a reading on the scale as 148 pounds. This person is acted on by
a)
No forces at all.
b)
Two forces of equal magnitude acting in opposite directions.
c)
Only one force of 148 pounds, as shown by the reading on the scale.
d)
Only one force, of 296 pounds (= 2 × 148 pounds)
|
Rohini Seth answered |
- Gravitational force is acting in the downward direction. As we know every action has a reaction.
- So, there is an equal and opposite force acting in opposite direction also.
Which one is correct if a bullet is fired from a rifle?- a)There is no motion of bullet and rifle.
- b)Rifle moves in backward direction and bullet moves in forward direction.
- c)Bullet and rifle both move in backward direction.
- d)Bullet moves in backward direction and rifle moves in forward direction.
Correct answer is option 'B'. Can you explain this answer?
Which one is correct if a bullet is fired from a rifle?
a)
There is no motion of bullet and rifle.
b)
Rifle moves in backward direction and bullet moves in forward direction.
c)
Bullet and rifle both move in backward direction.
d)
Bullet moves in backward direction and rifle moves in forward direction.
|
Aryan Will Be Back answered |
Here came the application of Newton's third law of motion.. A gun recoils when a shot is fired from it.. initially both the gun and the bullet are at rest so the total momentum of the system is constant ....
when a shot is fired the bullet moves forward pushing the gun backward this phenomenon is known as recoiling of gun...
Due to recoiling of gun a backward jerk is experience on the shoulder of the shooter..
when a shot is fired the bullet moves forward pushing the gun backward this phenomenon is known as recoiling of gun...
Due to recoiling of gun a backward jerk is experience on the shoulder of the shooter..
In high jump competition the athlete is made to fall on a cushioned bed to:- a)To decrease his momentum fast.
- b)Make him stop quickly.
- c)Increase the time to stop.
- d)Make him sleep comfortably.
Correct answer is option 'C'. Can you explain this answer?
In high jump competition the athlete is made to fall on a cushioned bed to:
a)
To decrease his momentum fast.
b)
Make him stop quickly.
c)
Increase the time to stop.
d)
Make him sleep comfortably.
|
|
Sagarika Tiwari answered |
Explanation:
The cushioned bed or mat used in high jump competition serves the purpose of decreasing the impact of the athlete's landing. When the athlete jumps over the bar, he gains a significant amount of momentum due to his speed and upward thrust. The cushioned bed helps to decrease this momentum gradually, thereby reducing the impact of the landing.
Increase the time to stop:
By decreasing the momentum gradually, the cushioned bed increases the time taken for the athlete to come to a complete stop. This is important because if the athlete were to land on a hard surface, the sudden stop could cause injuries to his joints and muscles. By increasing the time taken to stop, the cushioned bed reduces the risk of injury.
Conclusion:
Thus, option C, i.e., "Increase the time to stop" is the correct answer. The cushioned bed in high jump competition is designed to decrease the impact of the athlete's landing by reducing his momentum gradually and increasing the time taken to stop.
The cushioned bed or mat used in high jump competition serves the purpose of decreasing the impact of the athlete's landing. When the athlete jumps over the bar, he gains a significant amount of momentum due to his speed and upward thrust. The cushioned bed helps to decrease this momentum gradually, thereby reducing the impact of the landing.
Increase the time to stop:
By decreasing the momentum gradually, the cushioned bed increases the time taken for the athlete to come to a complete stop. This is important because if the athlete were to land on a hard surface, the sudden stop could cause injuries to his joints and muscles. By increasing the time taken to stop, the cushioned bed reduces the risk of injury.
Conclusion:
Thus, option C, i.e., "Increase the time to stop" is the correct answer. The cushioned bed in high jump competition is designed to decrease the impact of the athlete's landing by reducing his momentum gradually and increasing the time taken to stop.
The incorrect option regarding action-reaction pair is- a)they are equal and opposite
- b)they act on two different bodies
- c)they act only between bodies in contact
- d)their sum on/by a body is zero
Correct answer is option 'D'. Can you explain this answer?
The incorrect option regarding action-reaction pair is
a)
they are equal and opposite
b)
they act on two different bodies
c)
they act only between bodies in contact
d)
their sum on/by a body is zero
|
|
Anita Menon answered |
Since, action and reaction forces are equal in magnitude and opposite in directions. Therefore, there resultant is zero.
A cyclist of mass 30 kg exerts a force of 250 N to move his cycle. The acceleration is 4 ms−2. The force of friction between the road and tyres will be- a)120 N
- b)130 N
- c)150N
- d)115 N
Correct answer is option 'B'. Can you explain this answer?
A cyclist of mass 30 kg exerts a force of 250 N to move his cycle. The acceleration is 4 ms−2. The force of friction between the road and tyres will be
a)
120 N
b)
130 N
c)
150N
d)
115 N
|
Ankita jain answered |
Force - force of friction = mass × acceleration
250 - f = 30 × 4
f = 250 - 120
= 130N
250 - f = 30 × 4
f = 250 - 120
= 130N
When a fireman directs a powerful stream of water from a hose-pipe, the hose-pipe tends to go backward. This is due to:- a)Law of Inertia.
- b)Newton’s 3rd law.
- c)Law of conservation of charges.
- d)Law of conservation of energy
Correct answer is option 'B'. Can you explain this answer?
When a fireman directs a powerful stream of water from a hose-pipe, the hose-pipe tends to go backward. This is due to:
a)
Law of Inertia.
b)
Newton’s 3rd law.
c)
Law of conservation of charges.
d)
Law of conservation of energy
|
Hansa Sharma answered |
- According to the circumstances mentioned in the question, a powerful stream of water on a fire from a hose-pipe tend to go backward.
- This phenomenon is the practical life example of Newton's third law, " Every action has an equal and opposite reaction."
Force is defined as- a)change in momentum
- b)rate of change of momentum
- c)the quantity that opposes inertia
- d)the quantity that keeps the velocity constant
Correct answer is option 'B'. Can you explain this answer?
Force is defined as
a)
change in momentum
b)
rate of change of momentum
c)
the quantity that opposes inertia
d)
the quantity that keeps the velocity constant
|
|
Amit Kumar answered |
"The rate of change of momentum is called force”. “ When a net force acts on a body, it produces acceleration in thr body and will be equal to rate of change of momentum”. Hence , we found that Rate of change of momentum is equal to Force applied on the object .
If force, change in momentum and time are given by F, p and t respectively, then they are related b- a)F=pt
- b)F = p/t
- c)Ft2 = p
- d)p = F2t
Correct answer is option 'B'. Can you explain this answer?
If force, change in momentum and time are given by F, p and t respectively, then they are related b
a)
F=pt
b)
F = p/t
c)
Ft2 = p
d)
p = F2t
|
Geetika Shah answered |
The rate at which an object’s momentum changes is equal to the force acting on the object. If a force F acts on an object for a time Δt, then the change in the object's momentum is Δp = FΔt.
Which of the following is an equation of motion of a body?
- a)p = mv
- b)F = ma
- c)v = u + at
- d)Ft = mv - mu
Correct answer is option 'C'. Can you explain this answer?
Which of the following is an equation of motion of a body?
a)
p = mv
b)
F = ma
c)
v = u + at
d)
Ft = mv - mu
|
|
Arun Sharma answered |
v = u +at is the only equation of motion present here in the options. Hence, C is the correct answer
The rate of change of momentum with respect to time is measured in- a)kg ms-2
- b)kg ms-1
- c)kg m
- d)kg
Correct answer is option 'A'. Can you explain this answer?
The rate of change of momentum with respect to time is measured in
a)
kg ms-2
b)
kg ms-1
c)
kg m
d)
kg
|
|
Krishna Iyer answered |
We know, p = mv
Units of p, ⇒ kg ms-1
We have to measure, rate of change of momentum with respect to time ;
⇒ kg m s-2
Units of p, ⇒ kg ms-1
We have to measure, rate of change of momentum with respect to time ;
⇒ kg m s-2
Which is incorrect statement about action and reaction referred to Newton’s third law of motion?
A. They are equal
B. They are opposite
C. They act on same object
D. They act simultaneously
- a)(a) and (c) are correct
- b)(b) and (c) are correct
- c)(a), (b) and (c) are correct
- d)option c
Correct answer is option 'D'. Can you explain this answer?
Which is incorrect statement about action and reaction referred to Newton’s third law of motion?
A. They are equal
B. They are opposite
C. They act on same object
D. They act simultaneously
A. They are equal
B. They are opposite
C. They act on same object
D. They act simultaneously
a)
(a) and (c) are correct
b)
(b) and (c) are correct
c)
(a), (b) and (c) are correct
d)
option c
|
|
Amit Sharma answered |
Newton’s third law states that for every action (force) in nature there is an equal and opposite reaction. In other words, if object A exerts a force on object B, then object B also exerts an equal and opposite force on object A.
For every action, there is an equal and opposite reaction. The statement means that in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object equals the size of the force on the second object.
The objects interact. The action and reaction force always act on different objects. Two forces acting on the same object, even if they have the same magnitude and point in opposite directions, never form an action-reaction pair.
A man throws a ball weighing 200 g vertically upwards with a speed of 10m/s. Its momentum at the highest point of its flight will be:- a)2 kg. m/s
- b)2000 kg.m/s
- c)Insufficient data to find the momentum.
- d)zero.
Correct answer is option 'D'. Can you explain this answer?
A man throws a ball weighing 200 g vertically upwards with a speed of 10m/s. Its momentum at the highest point of its flight will be:
a)
2 kg. m/s
b)
2000 kg.m/s
c)
Insufficient data to find the momentum.
d)
zero.
|
Vikram Khanna answered |
Mass of the ball, m = 0.5 kg
Initial velocity, u = 10 m/s
Initial momentum = mu = 0.5 x 10 = 5 kg m/s
At the highest point, velocity of ball is zero.
So, momentum of the ball 0.5 x 0 = 0.
A child on a cart with wheels throws a sandbag forward. As a result:- a)He moves to the left.
- b)He moves backward.
- c)He moves forward.
- d)He moves to the right.
Correct answer is option 'B'. Can you explain this answer?
A child on a cart with wheels throws a sandbag forward. As a result:
a)
He moves to the left.
b)
He moves backward.
c)
He moves forward.
d)
He moves to the right.
|
|
Geetika Shah answered |
The child moves in the backward direction as a consequence of action-reaction law. Sandbag exerts an equal and opposite force in the backward direction.
Two equal masses m each moving in the opposite direction with the same speed v collide and stick to each other. The velocity of the combined mass is- a)v
- b)2v
- c)v/2
- d)zero
Correct answer is option 'D'. Can you explain this answer?
Two equal masses m each moving in the opposite direction with the same speed v collide and stick to each other. The velocity of the combined mass is
a)
v
b)
2v
c)
v/2
d)
zero
|
|
Swati Verma answered |
Total initial momentum = Total final momentum = zero
According to second law of Newton, force is the cause and the outcome is- a)acceleration
- b)velocity
- c)momentum
- d)time
Correct answer is option 'A'. Can you explain this answer?
According to second law of Newton, force is the cause and the outcome is
a)
acceleration
b)
velocity
c)
momentum
d)
time
|
|
Gaurav Kumar answered |
According to Newton’s second law of motion, also known as the Law of Force and Acceleration, a force upon an object's causes it to accelerate according to the formula:
Net force = mass x acceleration.
Net force = mass x acceleration.
So, the acceleration of the object is directly proportional to the force and inversely proportional to the mass.
Two balls A and B, of masses m and 2m are in motion with velocities 2v and v respectively. Compare the force needed to stop them in the same time- a)2 : 1
- b)1 : 2
- c)1 : 1
- d)None of the above
Correct answer is option 'C'. Can you explain this answer?
Two balls A and B, of masses m and 2m are in motion with velocities 2v and v respectively. Compare the force needed to stop them in the same time
a)
2 : 1
b)
1 : 2
c)
1 : 1
d)
None of the above
|
|
Vikram Khanna answered |
Since the change takes place in the same time: ratio of force needed to stop the balls is equal to the ratio of their momentum.
FA / FB = (m)(2v) / (2m)(v) = 1 : 1
An object of mass 2 kg is sliding with a constant velocity of 4 ms-1 on a frictional horizontal table. The force required to keep the object moving with same velocity is- a)2 N
- b)8 N
- c)32 N
- d)0 N
Correct answer is option 'D'. Can you explain this answer?
An object of mass 2 kg is sliding with a constant velocity of 4 ms-1 on a frictional horizontal table. The force required to keep the object moving with same velocity is
a)
2 N
b)
8 N
c)
32 N
d)
0 N
|
|
Raika Patel answered |
**Explanation:**
To understand why the correct answer is option 'D' (0 N), let's analyze the forces acting on the object:
1. **Weight:** The weight of the object is the force due to gravity acting vertically downwards. It can be calculated using the equation: Weight = mass x gravitational acceleration. In this case, the weight would be 2 kg x 9.8 m/s^2 = 19.6 N.
2. **Normal force:** The normal force is the force exerted by a surface to support the weight of an object resting on it. When an object is on a horizontal table, the normal force is equal in magnitude but opposite in direction to the weight of the object. So, the normal force in this case would also be 19.6 N.
3. **Frictional force:** The frictional force acts in the opposite direction to the motion of the object. It can be calculated using the equation: Frictional force = coefficient of friction x normal force. However, since the object is sliding with a constant velocity, we can conclude that the frictional force is equal in magnitude but opposite in direction to the force applied to keep the object moving with the same velocity. Therefore, the frictional force in this case is 0 N.
Now, let's consider the forces in the horizontal direction:
- Since the object is sliding with a constant velocity, the net force acting on it must be zero. This means that the force required to keep the object moving with the same velocity must be equal in magnitude but opposite in direction to the frictional force.
- As mentioned earlier, the frictional force is 0 N in this case, so the force required to keep the object moving with the same velocity is also 0 N.
- Hence, the correct answer is option 'D' (0 N).
Overall, the object is able to maintain a constant velocity of 4 m/s on the frictional horizontal table without any external force acting on it.
To understand why the correct answer is option 'D' (0 N), let's analyze the forces acting on the object:
1. **Weight:** The weight of the object is the force due to gravity acting vertically downwards. It can be calculated using the equation: Weight = mass x gravitational acceleration. In this case, the weight would be 2 kg x 9.8 m/s^2 = 19.6 N.
2. **Normal force:** The normal force is the force exerted by a surface to support the weight of an object resting on it. When an object is on a horizontal table, the normal force is equal in magnitude but opposite in direction to the weight of the object. So, the normal force in this case would also be 19.6 N.
3. **Frictional force:** The frictional force acts in the opposite direction to the motion of the object. It can be calculated using the equation: Frictional force = coefficient of friction x normal force. However, since the object is sliding with a constant velocity, we can conclude that the frictional force is equal in magnitude but opposite in direction to the force applied to keep the object moving with the same velocity. Therefore, the frictional force in this case is 0 N.
Now, let's consider the forces in the horizontal direction:
- Since the object is sliding with a constant velocity, the net force acting on it must be zero. This means that the force required to keep the object moving with the same velocity must be equal in magnitude but opposite in direction to the frictional force.
- As mentioned earlier, the frictional force is 0 N in this case, so the force required to keep the object moving with the same velocity is also 0 N.
- Hence, the correct answer is option 'D' (0 N).
Overall, the object is able to maintain a constant velocity of 4 m/s on the frictional horizontal table without any external force acting on it.
In a football and stone of same size, the inertia of
- a)Football is greater.
- b)Stone is greater.
- c)Both the objects is equal.
- d)None of the above.
Correct answer is option 'B'. Can you explain this answer?
In a football and stone of same size, the inertia of
a)
Football is greater.
b)
Stone is greater.
c)
Both the objects is equal.
d)
None of the above.
|
Jyoti Kapoor answered |
Inertia of stone is greater than the inertia of football because mass of stone is higher than the mass of football even both are of same size.
Which of the following does not happen? As an automobile accelerates suddenly,- a)a toy monkey hung from the roof moves back
- b)a standing person gets pushed back
- c)a bag at the roof gets displaced backward
- d)a person in the seat is pushed in front
Correct answer is option 'D'. Can you explain this answer?
Which of the following does not happen? As an automobile accelerates suddenly,
a)
a toy monkey hung from the roof moves back
b)
a standing person gets pushed back
c)
a bag at the roof gets displaced backward
d)
a person in the seat is pushed in front
|
|
Siddharth Sarkar answered |
When a vehicle accelerates and suddenly applies a break we possess what we call inertia. And when it suddenly applies a break we tend to retain that Velocity so we fall backwards thus satisfying the law of inertia or what is also called Newton's first law of motion.
The inertia of an object tends to cause the object - a)to increase its speed
- b)to decrease its speed
- c)to resist any change in the state of rest or of motion
- d)to decelerate due to friction
Correct answer is option 'C'. Can you explain this answer?
The inertia of an object tends to cause the object
a)
to increase its speed
b)
to decrease its speed
c)
to resist any change in the state of rest or of motion
d)
to decelerate due to friction
|
|
Swati Verma answered |
Inertia of an object is the tendency of the object to resist change in motion. The inertia is directly dependent on the mass of the body.
Inertia resist any change in its state of motion and is of three types:
Inertia resist any change in its state of motion and is of three types:
- Inertia of rest
- Inertia of motion
- Inertia of direction
Which is incorrect statement about action and reaction forces:a)They act on different objects.b)They are equal.c)They are opposite.d)They act on the same object. Correct answer is option 'D'. Can you explain this answer?
|
|
Neeharika Shah answered |
Action and Reaction Forces
Action and reaction forces are two forces that are always equal in magnitude but opposite in direction. These forces always act on different objects. Let's understand this concept in detail.
Action Force
An action force is a force that occurs when one object exerts force on another object. This force can be a push, pull, or any other force that one object exerts on another. For example, when you push a table, you are applying an action force on the table.
Reaction Force
A reaction force is a force that occurs when an object exerts force back on the object that applied the action force. This force is equal in magnitude but opposite in direction to the action force. For example, when you push a table, the table exerts a reaction force back on you.
Key Points
- Action and reaction forces always act on different objects.
- They are equal in magnitude but opposite in direction.
- They are always present in pairs.
- They occur simultaneously.
Incorrect Statement
The incorrect statement is option 'D', which says that action and reaction forces act on the same object. This statement is incorrect because action and reaction forces always act on different objects. When one object exerts force on another object, the second object exerts a reaction force back on the first object. For example, when you jump off a diving board, you exert a force on the board, and the board exerts a reaction force back on you. These forces always act on different objects.
Conclusion
In conclusion, action and reaction forces are equal in magnitude but opposite in direction. They always act on different objects and occur simultaneously. It is essential to understand this concept because it is a fundamental principle of physics that explains how objects move and interact with each other.
Action and reaction forces are two forces that are always equal in magnitude but opposite in direction. These forces always act on different objects. Let's understand this concept in detail.
Action Force
An action force is a force that occurs when one object exerts force on another object. This force can be a push, pull, or any other force that one object exerts on another. For example, when you push a table, you are applying an action force on the table.
Reaction Force
A reaction force is a force that occurs when an object exerts force back on the object that applied the action force. This force is equal in magnitude but opposite in direction to the action force. For example, when you push a table, the table exerts a reaction force back on you.
Key Points
- Action and reaction forces always act on different objects.
- They are equal in magnitude but opposite in direction.
- They are always present in pairs.
- They occur simultaneously.
Incorrect Statement
The incorrect statement is option 'D', which says that action and reaction forces act on the same object. This statement is incorrect because action and reaction forces always act on different objects. When one object exerts force on another object, the second object exerts a reaction force back on the first object. For example, when you jump off a diving board, you exert a force on the board, and the board exerts a reaction force back on you. These forces always act on different objects.
Conclusion
In conclusion, action and reaction forces are equal in magnitude but opposite in direction. They always act on different objects and occur simultaneously. It is essential to understand this concept because it is a fundamental principle of physics that explains how objects move and interact with each other.
The people in a bus are pushed backwards when the bus starts suddenly because of:- a)Inertia due to direction
- b)External force
- c)Inertia due to motion
- d)Inertia due to rest
Correct answer is option 'D'. Can you explain this answer?
The people in a bus are pushed backwards when the bus starts suddenly because of:
a)
Inertia due to direction
b)
External force
c)
Inertia due to motion
d)
Inertia due to rest
|
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Arjun Sharma answered |
This is due to inertia of rest of upper part of the passengers body when the bus or train suddenly starts moving, The lower part of the passenger’s body starts moving along with the bus or train while the upper part of the body has a tendency to remain in the state of rest due to inertia of rest, and hence falls backwards.
The acceleration of an object is- a)inversely proportional to its mass
- b)directly proportional to the applied force
- c)resisted by inertia
- d)all of the above
Correct answer is option 'D'. Can you explain this answer?
The acceleration of an object is
a)
inversely proportional to its mass
b)
directly proportional to the applied force
c)
resisted by inertia
d)
all of the above
|
|
Vikas Kapoor answered |
Newton's second law of motion can be formally stated as follows:- The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
While dusting a carpet we beat it with a stick because:- a)Force applied on the carpet.
- b)No inertia is involved.
- c)Inertia of motion removes the dust.
- d)Inertia of rest keeps the dust in its position.
Correct answer is option 'D'. Can you explain this answer?
While dusting a carpet we beat it with a stick because:
a)
Force applied on the carpet.
b)
No inertia is involved.
c)
Inertia of motion removes the dust.
d)
Inertia of rest keeps the dust in its position.
|
Sneha answered |
Because the dust particle is in rest position hence if we beat the carpet the inertia of rest will break and tey fall down .
Which one of the following statements is not correct for an object moving along a straight path in an accelerated motion?- a)Its speed keeps changing
- b)Its velocity always changes
- c)It always goes away from earth
- d)A force is always acting on it
Correct answer is option 'C'. Can you explain this answer?
Which one of the following statements is not correct for an object moving along a straight path in an accelerated motion?
a)
Its speed keeps changing
b)
Its velocity always changes
c)
It always goes away from earth
d)
A force is always acting on it
|
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Gaurav Kumar answered |
- The question states an accelerated motion of an object along a straight line, this implies a non zero force is acting on the object, which is increasing its velocity and speed.
- However the direction of force is not given so it can’t be determined that it is moving away from the earth, Hence the correct answer is C.
While catching a stone thrown by your friend you pul! the hands back to- a)avoid getting hurt
- b)increase the time to slow down
- c)decrease the time to slow down
- d)avoid the breaking of the stone
Correct answer is option 'B'. Can you explain this answer?
While catching a stone thrown by your friend you pul! the hands back to
a)
avoid getting hurt
b)
increase the time to slow down
c)
decrease the time to slow down
d)
avoid the breaking of the stone
|
Pooja Shah answered |
- While catching a fast moving cricket ball, a fielder in the ground gradually pulls his hand backward with the moving ball, in doing so, the fielder increases the time during which the high velocity of the moving ball decrease to zero.
- This, the acceleration of the ball is decreased and therefore, the impact of catching the fast moving ball is also reduced.
A plate, a ball and a child all have the same mass. The one having more inertia is the- a)plate
- b)ball
- c)child
- d)All have equal inertia
Correct answer is option 'D'. Can you explain this answer?
A plate, a ball and a child all have the same mass. The one having more inertia is the
a)
plate
b)
ball
c)
child
d)
All have equal inertia
|
|
Arvind Singh answered |
Inertia is the property of the body by virtue of which it resists any change in its state of rest or of uniform motion.
Inertia depends upon the mass of the object.
If the mass of a body is more, it will have more inertia.
As the mass of the plate, all and the child is the same, they all will have the same inertia.
Thus, the correct option is the same inertia for all due to the same mass.
Quantitative expression of force is given by:- a)Newton’s second law of motion.
- b)Newton’s third law of motion.
- c)Newton’s first law of motion.
- d)Newton’s law of gravitation.
Correct answer is option 'A'. Can you explain this answer?
Quantitative expression of force is given by:
a)
Newton’s second law of motion.
b)
Newton’s third law of motion.
c)
Newton’s first law of motion.
d)
Newton’s law of gravitation.
|
|
Vikas Kapoor answered |
Force can be calculated from Newton’s second law of motion which gives that force is the product of mass and acceleration.
A goalkeeper in a game of football pulls his hands backwards after holding the ball shot at the goal. This enables the goalkeeper to- a)exert larger force on the ball
- b)reduce the force exerted by the ball on hands
- c)increase the rate of change of momentum
- d)decrease the rate of change of momentum
Correct answer is option 'B'. Can you explain this answer?
A goalkeeper in a game of football pulls his hands backwards after holding the ball shot at the goal. This enables the goalkeeper to
a)
exert larger force on the ball
b)
reduce the force exerted by the ball on hands
c)
increase the rate of change of momentum
d)
decrease the rate of change of momentum
|
|
Pooja Shah answered |
A large force that acts in a very short duration of time is reffered to as impulsive force. This force which is large due to a high speed such as kick of a football may be disastrous as the momentum change is large and hence a goalkeeper holds his hand backwards in order to reduce the force exerted on his hands.
A resistive force of 16 N acts on a ball of mass 40 g continuously. If the initial velocity of the ball is 24 ms-1 ,the time taken by it to come to rest is:- a)0.04 s
- b)0.08 s
- c)0.06 s
- d)0.02 s
Correct answer is option 'C'. Can you explain this answer?
A resistive force of 16 N acts on a ball of mass 40 g continuously. If the initial velocity of the ball is 24 ms-1 ,the time taken by it to come to rest is:
a)
0.04 s
b)
0.08 s
c)
0.06 s
d)
0.02 s
|
Subham Gupta answered |
Mass of ball: m= 40 g = 0.040kg
resistive force: F = -16 N
thus resistive acceleration, a = F/m (because force, F= ma)
thus a = -400m/s^2
initial velocity, u = 24m/s
final velocity, v = 0m/s
Thus according to first equation of motion, v = u+at (t=timetaken)
t= 0.06s
Action and reaction forces are always:- a)Unequal and in opposite direction
- b)Unequal and in same direction.
- c)Equal and in same direction.
- d)Equal and in opposite direction
Correct answer is option 'D'. Can you explain this answer?
Action and reaction forces are always:
a)
Unequal and in opposite direction
b)
Unequal and in same direction.
c)
Equal and in same direction.
d)
Equal and in opposite direction
|
Vikas Rahar answered |
It is Newton's third law of motion that every action has an equal and opposite reaction
So, every action and reaction forces are equal and in opposite direction
So, every action and reaction forces are equal and in opposite direction
Bags at the top of a school van are tied using a string to avoid the effect of- a)inertia
- b)momentum
- c)force
- d)acceleration
Correct answer is option 'A'. Can you explain this answer?
Bags at the top of a school van are tied using a string to avoid the effect of
a)
inertia
b)
momentum
c)
force
d)
acceleration
|
Akshay Jain answered |
Explanation:
When a school van takes a sharp turn or applies brakes suddenly, the bags placed on the top of it tends to continue moving forward due to the property of inertia. Inertia is the tendency of an object to resist any change in its state of motion. Therefore, to avoid the effect of inertia, it is essential to tie the bags using a string.
Importance of String:
The string restricts the movement of the bags by holding them tightly at their place.
Other Options:
- Momentum: Momentum is the product of an object's mass and velocity. It is not related to the tying of bags on the top of a school van.
- Force: Force is the push or pull exerted on an object. Tying the bags with a string does not eliminate the effect of force acting on the bags.
- Acceleration: Acceleration is the rate at which an object changes its velocity. Tying the bags with a string does not eliminate the effect of acceleration acting on the bags.
When a school van takes a sharp turn or applies brakes suddenly, the bags placed on the top of it tends to continue moving forward due to the property of inertia. Inertia is the tendency of an object to resist any change in its state of motion. Therefore, to avoid the effect of inertia, it is essential to tie the bags using a string.
Importance of String:
The string restricts the movement of the bags by holding them tightly at their place.
Other Options:
- Momentum: Momentum is the product of an object's mass and velocity. It is not related to the tying of bags on the top of a school van.
- Force: Force is the push or pull exerted on an object. Tying the bags with a string does not eliminate the effect of force acting on the bags.
- Acceleration: Acceleration is the rate at which an object changes its velocity. Tying the bags with a string does not eliminate the effect of acceleration acting on the bags.
When a force is exerted on an object, it can change its-
A. State
B. Position
C. Shape
D. Direction- a)(a), (b) and (c) are correct
- b)(b) and (c) are correct
- c)(a) and (b) are correct
- d)All of these
Correct answer is option 'D'. Can you explain this answer?
When a force is exerted on an object, it can change its-
A. State
B. Position
C. Shape
D. Direction
A. State
B. Position
C. Shape
D. Direction
a)
(a), (b) and (c) are correct
b)
(b) and (c) are correct
c)
(a) and (b) are correct
d)
All of these
|
|
Pooja Shah answered |
D is the correct option.A force acting on an object causes the object to change its shape or size, to start moving, to stop moving, to accelerate or decelerate. When there's the interaction between two objects they exert a force on each other, these exerted forces are equal in size but opposite in direction.
Dust particles come out of a hanging carpet when we strike it with a stick because-
A Carpet starts moving forward and backward due to inertia of motion
B Dust particles remain at rest
C Dust particles starts moving forward due to inertia of motion
D Carpet remains at rest- a)(a), (b) and (c) are correct
- b)(a) and (b) are correct
- c)(b) and (c) are correct
- d)All of these
Correct answer is option 'B'. Can you explain this answer?
Dust particles come out of a hanging carpet when we strike it with a stick because-
A Carpet starts moving forward and backward due to inertia of motion
B Dust particles remain at rest
C Dust particles starts moving forward due to inertia of motion
D Carpet remains at rest
A Carpet starts moving forward and backward due to inertia of motion
B Dust particles remain at rest
C Dust particles starts moving forward due to inertia of motion
D Carpet remains at rest
a)
(a), (b) and (c) are correct
b)
(a) and (b) are correct
c)
(b) and (c) are correct
d)
All of these
|
|
Tara Singh answered |
Inertia of Motion:
When an object is at rest, it tends to stay at rest, and when it is in motion, it tends to stay in motion with the same speed and in the same direction unless acted upon by an external force. This property of objects is known as inertia of motion.
Explanation:
When we strike a hanging carpet with a stick, several things happen that cause dust particles to come out of the carpet. Let's analyze each option to understand the phenomenon:
A. Carpet starts moving forward and backward due to inertia of motion:
This option suggests that the carpet starts moving forward and backward due to its inertia of motion. However, this is not correct because the carpet does not move significantly when struck with a stick. It may vibrate or oscillate slightly, but it does not move back and forth significantly.
B. Dust particles remain at rest:
This option states that the dust particles remain at rest. Dust particles are usually settled on the surface of the carpet due to gravity, and they do not have any significant motion or inertia. Therefore, this option is correct because the dust particles do not move on their own.
C. Dust particles start moving forward due to inertia of motion:
This option suggests that the dust particles start moving forward due to their inertia of motion. However, dust particles do not have any significant inertia of motion. They remain at rest unless acted upon by an external force. Therefore, this option is incorrect.
D. Carpet remains at rest:
This option states that the carpet remains at rest when struck with a stick. While the carpet may vibrate or oscillate slightly, it does not move significantly from its original position. Therefore, this option is correct.
Conclusion:
When we strike a hanging carpet with a stick, the dust particles come out of the carpet because the carpet remains at rest, and the dust particles, being settled on the surface, are dislodged due to the impact of the strike. The dust particles do not have any significant motion or inertia of their own.
When an object is at rest, it tends to stay at rest, and when it is in motion, it tends to stay in motion with the same speed and in the same direction unless acted upon by an external force. This property of objects is known as inertia of motion.
Explanation:
When we strike a hanging carpet with a stick, several things happen that cause dust particles to come out of the carpet. Let's analyze each option to understand the phenomenon:
A. Carpet starts moving forward and backward due to inertia of motion:
This option suggests that the carpet starts moving forward and backward due to its inertia of motion. However, this is not correct because the carpet does not move significantly when struck with a stick. It may vibrate or oscillate slightly, but it does not move back and forth significantly.
B. Dust particles remain at rest:
This option states that the dust particles remain at rest. Dust particles are usually settled on the surface of the carpet due to gravity, and they do not have any significant motion or inertia. Therefore, this option is correct because the dust particles do not move on their own.
C. Dust particles start moving forward due to inertia of motion:
This option suggests that the dust particles start moving forward due to their inertia of motion. However, dust particles do not have any significant inertia of motion. They remain at rest unless acted upon by an external force. Therefore, this option is incorrect.
D. Carpet remains at rest:
This option states that the carpet remains at rest when struck with a stick. While the carpet may vibrate or oscillate slightly, it does not move significantly from its original position. Therefore, this option is correct.
Conclusion:
When we strike a hanging carpet with a stick, the dust particles come out of the carpet because the carpet remains at rest, and the dust particles, being settled on the surface, are dislodged due to the impact of the strike. The dust particles do not have any significant motion or inertia of their own.
Newton’s third law of motion explains the two forces namely ‘action’ and ‘reaction’ coming into action when the two bodies are in contact with each other. These two forces:
- a) Always act on the same body
- b)Have same magnitude and direction
- c)Acts on either body at normal to each other
- d)Always act on the different bodies in opposite directions
Correct answer is option 'D'. Can you explain this answer?
Newton’s third law of motion explains the two forces namely ‘action’ and ‘reaction’ coming into action when the two bodies are in contact with each other. These two forces:
a)
Always act on the same body
b)
Have same magnitude and direction
c)
Acts on either body at normal to each other
d)
Always act on the different bodies in opposite directions
|
Netbhet Solutions answered |
Always act on the different bodies in opposite directions.
Find the incorrect statement about Newton’s law of action and reaction. Action and reaction
- a)are equal in magnitude
- b)act on same bodies
- c)act simultaneously
- d)are different in direction
Correct answer is option 'B'. Can you explain this answer?
Find the incorrect statement about Newton’s law of action and reaction. Action and reaction
a)
are equal in magnitude
b)
act on same bodies
c)
act simultaneously
d)
are different in direction
|
Ishan Choudhury answered |
Newton's third law states that for every action, there is an equal and opposite reaction. This means that the forces are equal in magnitude (1), act simultaneously (3), and are opposite in direction (4). However, they act on different bodies, not the same one.
An Object moving along a straight path with an accelerated motion. The correct statement about the object-
A. Its velocity keeps changing
B. Its speed keeps changing
C. A force is always acting on it
D. Its mass keeps on changing- a)(a) and (b) are correct
- b)(b) and (c) are correct
- c)(a), (b) and (c) are correct
- d)All of these
Correct answer is option 'C'. Can you explain this answer?
An Object moving along a straight path with an accelerated motion. The correct statement about the object-
A. Its velocity keeps changing
B. Its speed keeps changing
C. A force is always acting on it
D. Its mass keeps on changing
A. Its velocity keeps changing
B. Its speed keeps changing
C. A force is always acting on it
D. Its mass keeps on changing
a)
(a) and (b) are correct
b)
(b) and (c) are correct
c)
(a), (b) and (c) are correct
d)
All of these
|
|
Pooja Shah answered |
The correct option is Option C.
This is because when acceleration increases so will speed and velocity. As acceleration is a type of accelerated force a force will always act on the body.
This is because when acceleration increases so will speed and velocity. As acceleration is a type of accelerated force a force will always act on the body.
Same amount of force is acting on a car and bus. It the ratio of the mass of the bus and the car is 50:1, calculate the ratio of the acceleration produced in the bus to the acceleration produced in the car
- a)50:1
- b)1:50
- c)1:25
- d)25:1
Correct answer is option 'B'. Can you explain this answer?
Same amount of force is acting on a car and bus. It the ratio of the mass of the bus and the car is 50:1, calculate the ratio of the acceleration produced in the bus to the acceleration produced in the car
a)
50:1
b)
1:50
c)
1:25
d)
25:1
|
|
Vikram Khanna answered |
We know thatf=malet acceleration of bus= a1" " " car=a2let mass of bus=m1" " " car=m2ATQf=m1a1=m2a2a1=f/m1a2=f/m2so ratio=(f/m2)/(f/m1)=m1/m2=25/1=25:1The answer is d
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