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Important Questions (1 mark): Forces & Laws of Motion - Class 9 MCQ


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25 Questions MCQ Test - Important Questions (1 mark): Forces & Laws of Motion

Important Questions (1 mark): Forces & Laws of Motion for Class 9 2024 is part of Class 9 preparation. The Important Questions (1 mark): Forces & Laws of Motion questions and answers have been prepared according to the Class 9 exam syllabus.The Important Questions (1 mark): Forces & Laws of Motion MCQs are made for Class 9 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Important Questions (1 mark): Forces & Laws of Motion below.
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Important Questions (1 mark): Forces & Laws of Motion - Question 1

Identify the incorrect statement

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 1

Weight of the body is the force by which it is attracted by earth.
The spring force is the force exerted by a compressed or stretched spring upon any object that is attached to it. An object that compresses or stretches a spring is always acted upon by a force that restores the object to its rest or equilibrium position. So, the spring force does not always pushes a body.
Frictional force always acts opposite to the surface of contact.

Important Questions (1 mark): Forces & Laws of Motion - Question 2

Some of the leaves may get detached from a tree if we vigorously shake its branch because of

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 2

If a branch of a tree is vigorously shaken, some of the leaves may get detached from tree due to inertia of rest. The leaves tend to remain in rest but branches come in motion.

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Important Questions (1 mark): Forces & Laws of Motion - Question 3

Essential characteristic of equilibrium is

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 3

At equilibrium, the acceleration is equal to zero. So, there is no net change in acceleration of the moving body.

Important Questions (1 mark): Forces & Laws of Motion - Question 4

“Inflated balloon lying on the surface of a floor moves forward when pierced with a pin. The above mentioned phenomenon is due to

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 4

Inflated balloon lying on the surface of a floor moves forward when pierced with a pin due to Newton’s third law of motion. The air coming out of the balloon forces the balloon in opposite direction.

Important Questions (1 mark): Forces & Laws of Motion - Question 5

A unit of force is

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 5

The SI unit of force is Newton, which is equal to the mass/ acceleration. 
Newton =Kg/ms2= Kgms−2.

Important Questions (1 mark): Forces & Laws of Motion - Question 6

Inertia is the property of a body by virtue of which the body is

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 6

Inertia is the property of a body by virtue of which the body unable to change the state of rest or state of motion and direction as inertia is the tendency to oppose the change in state or direction.

Important Questions (1 mark): Forces & Laws of Motion - Question 7

To every action there is an,

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 7

To every action, there is an equal and opposite reaction. This is the newton’s third law of motion.

Important Questions (1 mark): Forces & Laws of Motion - Question 8

The change in the momentum of a body in 0.01 second is 10 kg ms-1. The force acting on this body is

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 8

The force acting on a body is equal to rate of change of momentum. Change of momentum = 10 Kg/s, time taken = 0.01 second. Force = 10/0.01 = 1000N.

Important Questions (1 mark): Forces & Laws of Motion - Question 9

10dyne is equal to

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 9

One Newton (1N) is equal to 105 dyne. Both dyne and Newton is unit of force.

Important Questions (1 mark): Forces & Laws of Motion - Question 10

Which has more inertia?

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 10

Inertia of the body is proportional to the mass of the body. 5 Rs coin is heavier than 5 Rs note and 1 Rs coins. So, inertia of 5 Rs coin more than others.

Important Questions (1 mark): Forces & Laws of Motion - Question 11

“Forces always occur in pairs”. From which law can we conclude the above statement?

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 11

The force always occurs in pairs. According to third law of motion, there is equal and opposite reaction. So two force, action and reaction acts in pair always.

Important Questions (1 mark): Forces & Laws of Motion - Question 12

Statement A: Rocket can propel its self in vacuum. 
Statement B: Newton’s laws are universal. 
Which of the two statements is true?

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 12

Rocket moves forward according to newton’s third law of motion. The gas and other substance coming out from the tail push the rocket in forward direction. Newton’s laws are universal.

Important Questions (1 mark): Forces & Laws of Motion - Question 13

A force has

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 13

A force has both magnitude as well as direction. Force is a vector quantity. Force is the product of mass and acceleration.

Important Questions (1 mark): Forces & Laws of Motion - Question 14

A high jumper runs for a while before taking high jump so that the inertia of __________ help him in taking a long jump.

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 14

A high jumper runs for a while before taking high jump so that the inertia of motion help him in taking a long jump. Inertia of motion tends to remain in state of motion.

Important Questions (1 mark): Forces & Laws of Motion - Question 15

Frictional force

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 15

Frictional force always opposes relative motion between the surfaces of contact. The direction of force is always in opposite direction.

Important Questions (1 mark): Forces & Laws of Motion - Question 16

A ball is dropped from a height of 10m. Ball is embedded in sand of 1m and stops.

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 16

When body is dropped from height, the potential energy deceases and kinetic energy increases. A ball dropped from height will conserve only kinetic energy.

Important Questions (1 mark): Forces & Laws of Motion - Question 17

Statement A: Gravitational force is the weakest force in nature 
Statement B: Electrostatic force is the example of non – contact force
Which of the above two statement is true?

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 17

Gravitational force is very weak force as it depends upon mass of the body and distance between two objects. Electrostatic force is non-contact force.

Important Questions (1 mark): Forces & Laws of Motion - Question 18

If P and Q are two bodies with masses 10 kg and 5kg respectively, then which body has more inertia?

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 18

The inertia of the body is proportional to mass of the body. So, body P with masses 10 kg will have more inertia in comparison to body Q of mass 5 kg.

Important Questions (1 mark): Forces & Laws of Motion - Question 19

‘Any two forces which are equal and opposite form an action and reaction pair’ The above statement is

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 19

The two forces acting on same body, which are equal and opposite direction forms action and reaction. This is the newton’s thirds law of motion.

Important Questions (1 mark): Forces & Laws of Motion - Question 20

Two bodies of masses 1kg and 5kg are dropped gently from the top of a tower. At a point 50cm from the ground both the bodies will have the same

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 20

The velocity of the body falling towards depends upon gravitational force acting on it. So, both the body of masses 1 kg and 5 kg will have same velocity at particular height and fall at same time at the ground.

Important Questions (1 mark): Forces & Laws of Motion - Question 21

Ayush hits a cricket ball which than rolls of a level ground after covering a short distance, the ball comes to rest. The ball slows to a stop because

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 21

The ball moving on level ground comes to rest after covering a short distance due to frictional force acting on it. So, ball slows to a stop because there is a force on the ball opposing the motion.

Important Questions (1 mark): Forces & Laws of Motion - Question 22

In a football and stone of same size, the inertia of 
A. Football is greater
B. Football is lesser 
C. Stone is greater 
D. Stone is lesser 

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 22

Inertia is directly proportional to the mass of the body. Higher the mass of the body, the higher will be the inertia.

Important Questions (1 mark): Forces & Laws of Motion - Question 23

“Action and reaction are equal and opposite but even then they do not cancel each other” the above statement is

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 23

Action and reaction are equal and opposite but even they do not cancel each other because they acts in opposite direction. Hence the statement is correct.

Important Questions (1 mark): Forces & Laws of Motion - Question 24

Statement A: Calculus, a new branch of mathematics was stated by Newton. 
Statement B: If mass remains same, doubling the force will reduce the acceleration to half. 
Which of the above two statements is true

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 24

The branch of mathematics, called Calculus was stated by Newton. Force is the product of mass and acceleration. So, acceleration= force /mass. Doubling of force will increase the acceleration if mass is kept same.

Important Questions (1 mark): Forces & Laws of Motion - Question 25

Match the following with correct response.

Detailed Solution for Important Questions (1 mark): Forces & Laws of Motion - Question 25

As described by the third of Newton's laws of motion of classical mechanics, all forces occur in pairs such that if one object exerts a force on another object, then the second object exerts an equal and opposite reaction force on the first.
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.
Momentum is not a scalar quantity. Momentum is a vector, which means it has a magnitude and a direction. Linear momentum is the product of an object's.
When two forces acting on an object are not equal in size, we say that they are unbalanced forces. The overall force acting on the object is called the resultant force . If the forces are balanced, the resultant force is zero. An object having balanced forces definitely cannot be accelerating. This means that it could be at rest and staying at rest or could be in motion at constant velocity.

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