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All questions of Gravitation & Floatation for Grade 9 Exam
The mass of the body on moon is 40kg, what is the weight on the earth. - a) 240kg
- b) 392N
- c) 240N
- d) 400kg
Correct answer is option 'B'. Can you explain this answer?
The mass of the body on moon is 40kg, what is the weight on the earth.
a)
240kg
b)
392N
c)
240N
d)
400kg
|
Arvind Singh answered |
Mass of body on moon is 40 kg.
Weight on earth = mg
=40kg�9.8m/s^2
=392N.
Thrust exerted by an iron cuboid when placed on sand is equal to
- a)mass of cuboid
- b)mass per unit surface area
- c)weight of cuboid
- d)weight per unit surface area
Correct answer is option 'C'. Can you explain this answer?
Thrust exerted by an iron cuboid when placed on sand is equal to
a)
mass of cuboid
b)
mass per unit surface area
c)
weight of cuboid
d)
weight per unit surface area
|
Swara Deshpande answered |
Thrust Exerted by an Iron Cuboid on Sand
Thrust is defined as the force exerted by an object perpendicular to the surface it is in contact with. When an iron cuboid is placed on sand, it exerts a force on the sand due to its weight.
Factors Affecting Thrust
The thrust exerted by an iron cuboid on sand depends on the following factors:
1. Weight of the cuboid
2. Surface area of the base of the cuboid
3. Nature of the sand
Calculation of Thrust
The thrust exerted by an iron cuboid on sand can be calculated using the formula:
Thrust = Weight of the cuboid
This is because the weight of the cuboid is the force with which it is pressing down on the sand, and this force is transmitted to the sand as thrust.
Explanation of Options
a) Mass of cuboid - The mass of the cuboid is not directly related to the thrust exerted by it on sand. It is the weight of the cuboid that matters.
b) Mass per unit surface area - Mass per unit surface area is not a relevant parameter for calculating the thrust exerted by an object on a surface.
c) Weight of cuboid - The weight of the cuboid is the force with which it is pressing down on the sand, and this force is transmitted to the sand as thrust. Therefore, the correct answer is option 'C'.
d) Weight per unit surface area - Weight per unit surface area is not a relevant parameter for calculating the thrust exerted by an object on a surface.
Conclusion
The thrust exerted by an iron cuboid on sand is equal to its weight. This is because the weight of the cuboid is the force with which it is pressing down on the sand, and this force is transmitted to the sand as thrust.
Thrust is defined as the force exerted by an object perpendicular to the surface it is in contact with. When an iron cuboid is placed on sand, it exerts a force on the sand due to its weight.
Factors Affecting Thrust
The thrust exerted by an iron cuboid on sand depends on the following factors:
1. Weight of the cuboid
2. Surface area of the base of the cuboid
3. Nature of the sand
Calculation of Thrust
The thrust exerted by an iron cuboid on sand can be calculated using the formula:
Thrust = Weight of the cuboid
This is because the weight of the cuboid is the force with which it is pressing down on the sand, and this force is transmitted to the sand as thrust.
Explanation of Options
a) Mass of cuboid - The mass of the cuboid is not directly related to the thrust exerted by it on sand. It is the weight of the cuboid that matters.
b) Mass per unit surface area - Mass per unit surface area is not a relevant parameter for calculating the thrust exerted by an object on a surface.
c) Weight of cuboid - The weight of the cuboid is the force with which it is pressing down on the sand, and this force is transmitted to the sand as thrust. Therefore, the correct answer is option 'C'.
d) Weight per unit surface area - Weight per unit surface area is not a relevant parameter for calculating the thrust exerted by an object on a surface.
Conclusion
The thrust exerted by an iron cuboid on sand is equal to its weight. This is because the weight of the cuboid is the force with which it is pressing down on the sand, and this force is transmitted to the sand as thrust.
A sharp edge blade is more effective in cutting than a blunt blade due to- a)Low force
- b)Low pressure
- c)Large contact area
- d)Small contact area
Correct answer is option 'D'. Can you explain this answer?
A sharp edge blade is more effective in cutting than a blunt blade due to
a)
Low force
b)
Low pressure
c)
Large contact area
d)
Small contact area
|
Rydhim Sharma answered |
As knife have less number of atoms and that's why it can seperate the atoms of material by dugging into the space between then easily
1 kg wt is equal to- a)9.8 N
- b)980 N
- c)98 N
- d)None of these
Correct answer is option 'A'. Can you explain this answer?
1 kg wt is equal to
a)
9.8 N
b)
980 N
c)
98 N
d)
None of these
|
Saikat Shah answered |
Conversion of 1 kg wt to Newtons
Definition of kilogram weight (kg wt)
Kilogram weight (kg wt) is a unit of force used in the metric system. It is defined as the weight of a kilogram mass under standard gravity.
Definition of Newton (N)
Newton (N) is the SI unit of force. It is defined as the force required to accelerate a mass of one kilogram at a rate of one meter per second per second.
Formula for conversion of kg wt to N
The formula for converting kg wt to N is:
1 kg wt = 9.8 N
Explanation of the formula
The conversion factor for kg wt to N is the acceleration due to gravity (g). In SI units, the value of g is approximately 9.8 m/s2. Therefore, the weight of a mass of 1 kg under standard gravity is:
Weight = Mass x Acceleration due to gravity
= 1 kg x 9.8 m/s2
= 9.8 N
Conclusion
Therefore, 1 kg wt is equal to 9.8 N. This conversion factor is used to convert between units of force in the metric system.
Definition of kilogram weight (kg wt)
Kilogram weight (kg wt) is a unit of force used in the metric system. It is defined as the weight of a kilogram mass under standard gravity.
Definition of Newton (N)
Newton (N) is the SI unit of force. It is defined as the force required to accelerate a mass of one kilogram at a rate of one meter per second per second.
Formula for conversion of kg wt to N
The formula for converting kg wt to N is:
1 kg wt = 9.8 N
Explanation of the formula
The conversion factor for kg wt to N is the acceleration due to gravity (g). In SI units, the value of g is approximately 9.8 m/s2. Therefore, the weight of a mass of 1 kg under standard gravity is:
Weight = Mass x Acceleration due to gravity
= 1 kg x 9.8 m/s2
= 9.8 N
Conclusion
Therefore, 1 kg wt is equal to 9.8 N. This conversion factor is used to convert between units of force in the metric system.
Weight of a body on earth is 48 N; its weight on moon is- a)98 N
- b)48 N
- c)9.8 N
- d)8 N
Correct answer is option 'D'. Can you explain this answer?
Weight of a body on earth is 48 N; its weight on moon is
a)
98 N
b)
48 N
c)
9.8 N
d)
8 N
|
|
Himaja Ammu answered |
Weight on moon=1/6of weight on earth =1/6×48 =8N
The pressure exerted by water (density = 103 kg/m3) on the bottom surface (2m × 4m) of tank having dimensions 2m × 4m × 2m is
- a)2.96 × 105 Pa
- b)1.96 × 105 Pa
- c)1.80 × 104 Pa
- d)1.96 × 104 Pa
Correct answer is option 'D'. Can you explain this answer?
The pressure exerted by water (density = 103 kg/m3) on the bottom surface (2m × 4m) of tank having dimensions 2m × 4m × 2m is
a)
2.96 × 105 Pa
b)
1.96 × 105 Pa
c)
1.80 × 104 Pa
d)
1.96 × 104 Pa
|
EduRev Class 9 answered |
The pressure exerted by a fluid in a tank is given by the formula:
P = ρgh
where
- ρ (rho) is the density of the fluid (water, 103 kg/m3)
- g is the acceleration due to gravity (approximately 9.8 m/s2)
- h is the height of the fluid column (2 meters)
Substitute the values into the formula:
- P = 103 kg/m3 × 9.8 m/s2 × 2 m
- P = 1.96 × 104 Pa
Therefore, the correct answer is:
D: 1.96 × 104 Pa
Apple falls towards the earth but the earth does not move towards the apple because- a)only earth exerts force on apple, apple does not exert force on earth
- b)apple experiences greater force than the earth
- c)only apple exerts force on earth, earth does not exert force on apple
- d)acceleration is inversely proportional to mass, so acceleration of earth is negligible.
Correct answer is option 'D'. Can you explain this answer?
Apple falls towards the earth but the earth does not move towards the apple because
a)
only earth exerts force on apple, apple does not exert force on earth
b)
apple experiences greater force than the earth
c)
only apple exerts force on earth, earth does not exert force on apple
d)
acceleration is inversely proportional to mass, so acceleration of earth is negligible.
|
Vikram Khanna answered |
Apple falls towards the earth, but the earth does not move towards the apple because acceleration is inversely proportional to mass. Earth’s mass being extremly large as compared to apple, it has negligible acceleration towards the apple.
Mass of oil is 11040 kg and volume is 12 m³, its density would be- a)92 kg m-3
- b)920 kg m-3
- c)9.2 kg m-3
- d)1.08 × 10-3
Correct answer is option 'B'. Can you explain this answer?
Mass of oil is 11040 kg and volume is 12 m³, its density would be
a)
92 kg m-3
b)
920 kg m-3
c)
9.2 kg m-3
d)
1.08 × 10-3
|
Gaurav Kumar answered |
Density,
ρ = M / V = 11040 / 12
= 920 kg/m³
ρ = M / V = 11040 / 12
= 920 kg/m³
Maximum weight of a body is- a)At the centre of the earth
- b)Inside the earth
- c)On the surface of the earth
- d)Above the surface of earth
Correct answer is option 'C'. Can you explain this answer?
Maximum weight of a body is
a)
At the centre of the earth
b)
Inside the earth
c)
On the surface of the earth
d)
Above the surface of earth
|
Ritu Saxena answered |
At the center gravity is 0 ,gravity decreases as we go down into the earth ,also it decreases as we go above the surface of earth.
So weight w = mg is maximum on the surface because at surface the value of g is maximum.
So weight w = mg is maximum on the surface because at surface the value of g is maximum.
A rectangular block of wood of dimensions 40cm x 20cm x 10cm is kept on a table top. The pressure is greatest when it is rested on- a)equal for all cases
- b)20cm x 10 cm
- c)40cm x 10cm
- d)40cm x 20cm
Correct answer is option 'B'. Can you explain this answer?
A rectangular block of wood of dimensions 40cm x 20cm x 10cm is kept on a table top. The pressure is greatest when it is rested on
a)
equal for all cases
b)
20cm x 10 cm
c)
40cm x 10cm
d)
40cm x 20cm
|
|
Raghav Bansal answered |
Mass of the Wooden block, m = 5Kg
Thrust due to wooden block, Mg = 5kg x 9.8 m/s² = 49N
Thrust due to wooden block, Mg = 5kg x 9.8 m/s² = 49N
(a) Surface area of 20 Cm x 10 Cm surface ,
A = (20 x 10) cm² = (0.2 x 0.1) m² = 0.02 m²
P = mg / A = 49 N / 0.02 m² = 49/0.02 N/m²
Or Pressure, P = 2450 N/m²
A = (20 x 10) cm² = (0.2 x 0.1) m² = 0.02 m²
P = mg / A = 49 N / 0.02 m² = 49/0.02 N/m²
Or Pressure, P = 2450 N/m²
(b) Surface area of 40 cm x 20 cm surface,
A = ( 40 x 20) cm² = ( 0.4 x 0.2 ) m² = 0.08 m²
P = mg / A = 49 N / 0.08 m² = 49/0.08 N/m²
Or Pressure, P = 612.5 N/m²
A = ( 40 x 20) cm² = ( 0.4 x 0.2 ) m² = 0.08 m²
P = mg / A = 49 N / 0.08 m² = 49/0.08 N/m²
Or Pressure, P = 612.5 N/m²
An object exerts a force F on a surface of surface area A. The pressure P acting on the surface is given by- a)P = FA
- b)P = F/A
- c)P = F/A2
- d)P = A/F
Correct answer is option 'B'. Can you explain this answer?
An object exerts a force F on a surface of surface area A. The pressure P acting on the surface is given by
a)
P = FA
b)
P = F/A
c)
P = F/A2
d)
P = A/F
|
Ankita Choudhary. answered |
Yes this is because pressure = force/Area
so p=f/a ...
so p=f/a ...
A ball is thrown vertically upwards with a velocity ‘u’. The velocity with which it falls to the earth again is:- a)Greater than ‘u’
- b)Greater than or equal to ‘u’
- c)Equal to ‘u’
- d)Less than ‘u’
Correct answer is option 'C'. Can you explain this answer?
A ball is thrown vertically upwards with a velocity ‘u’. The velocity with which it falls to the earth again is:
a)
Greater than ‘u’
b)
Greater than or equal to ‘u’
c)
Equal to ‘u’
d)
Less than ‘u’
|
|
Anita Menon answered |
For vertically upward motion: g is negative as it opposes the motion.
v = u – gt
0 = u – gt
t = u/g (1)
For vertically downward motion: g is positive as it is in the direction of motion.
v = u + gt
v = 0 + gt
t = v/g (2)
From equation 1 and 2
v = u
A body is weighed at the poles and then at the equator. The weight- a)At the equator will be greater than at the poles
- b)At the poles will be greater than at the equator
- c)At the poles will be equal to the weight at the equator
- d)Depends upon the object
Correct answer is option 'B'. Can you explain this answer?
A body is weighed at the poles and then at the equator. The weight
a)
At the equator will be greater than at the poles
b)
At the poles will be greater than at the equator
c)
At the poles will be equal to the weight at the equator
d)
Depends upon the object
|
|
Seema Bajpai answered |
B is the key to success
What is the mass of a body whose weight is 59 N? Take g = 9.8 m/s2- a)5 kg
- b)9 kg
- c)6 kg
- d)50 kg
Correct answer is 'C'. Can you explain this answer?
What is the mass of a body whose weight is 59 N? Take g = 9.8 m/s2
a)
5 kg
b)
9 kg
c)
6 kg
d)
50 kg
|
Nirali Shah answered |
To find the mass of a body, we can use the formula:
Weight = mass × acceleration due to gravity (g)
Given that the weight of the body is 59 N and the acceleration due to gravity is 9.8 m/s^2, we can rearrange the formula to solve for mass:
mass = weight / acceleration due to gravity
Substituting the given values:
mass = 59 N / 9.8 m/s^2
Calculating this equation gives us:
mass ≈ 6 kg
Therefore, the mass of the body is approximately 6 kg.
Explanation:
- Weight is the force exerted by a body due to gravity, and it is measured in Newtons (N).
- The acceleration due to gravity, denoted by 'g', is the acceleration an object experiences due to the gravitational force. On Earth, the average value of g is approximately 9.8 m/s^2.
- The formula weight = mass × acceleration due to gravity relates weight, mass, and acceleration due to gravity.
- To find the mass, we rearrange the formula and divide both sides by acceleration due to gravity.
- By substituting the given values of weight (59 N) and acceleration due to gravity (9.8 m/s^2) into the formula, we can calculate the mass.
- The final result is approximately 6 kg.
Weight = mass × acceleration due to gravity (g)
Given that the weight of the body is 59 N and the acceleration due to gravity is 9.8 m/s^2, we can rearrange the formula to solve for mass:
mass = weight / acceleration due to gravity
Substituting the given values:
mass = 59 N / 9.8 m/s^2
Calculating this equation gives us:
mass ≈ 6 kg
Therefore, the mass of the body is approximately 6 kg.
Explanation:
- Weight is the force exerted by a body due to gravity, and it is measured in Newtons (N).
- The acceleration due to gravity, denoted by 'g', is the acceleration an object experiences due to the gravitational force. On Earth, the average value of g is approximately 9.8 m/s^2.
- The formula weight = mass × acceleration due to gravity relates weight, mass, and acceleration due to gravity.
- To find the mass, we rearrange the formula and divide both sides by acceleration due to gravity.
- By substituting the given values of weight (59 N) and acceleration due to gravity (9.8 m/s^2) into the formula, we can calculate the mass.
- The final result is approximately 6 kg.
If the mass of a body is M on the sufrace of the earth, then its mass on the surface of the moon will be- a)M/6
- b)M
- c)M + 6
- d)Zero
Correct answer is option 'B'. Can you explain this answer?
If the mass of a body is M on the sufrace of the earth, then its mass on the surface of the moon will be
a)
M/6
b)
M
c)
M + 6
d)
Zero
|
Aaditya Saini answered |
Mass of body on surface of Earth vs. Moon
Explanation:
On the surface of the Earth, the gravitational force acting on a body is given by:
F = mg
where F is the force of attraction due to gravity, m is the mass of the body and g is the acceleration due to gravity.
On the surface of the Moon, the acceleration due to gravity is much lower than on Earth. The value of g on the surface of the Moon is approximately 1/6th of its value on Earth.
Therefore, the force of attraction due to gravity on the surface of the Moon is given by:
F' = mg/6
where m is the same as the mass of the body on Earth.
The mass of the body, however, remains the same on the surface of the Moon as it was on the surface of the Earth, since mass is an intrinsic property of an object and does not change with location.
Hence, the correct answer is option B, which states that the mass of the body on the surface of the Moon is the same as its mass on the surface of the Earth.
Explanation:
On the surface of the Earth, the gravitational force acting on a body is given by:
F = mg
where F is the force of attraction due to gravity, m is the mass of the body and g is the acceleration due to gravity.
On the surface of the Moon, the acceleration due to gravity is much lower than on Earth. The value of g on the surface of the Moon is approximately 1/6th of its value on Earth.
Therefore, the force of attraction due to gravity on the surface of the Moon is given by:
F' = mg/6
where m is the same as the mass of the body on Earth.
The mass of the body, however, remains the same on the surface of the Moon as it was on the surface of the Earth, since mass is an intrinsic property of an object and does not change with location.
Hence, the correct answer is option B, which states that the mass of the body on the surface of the Moon is the same as its mass on the surface of the Earth.
Consider a satellite going round the earth in a circular orbit. Which of the following statements is wrong ?
- a)It is a freely falling body
- b)It is moving with constant speed
- c)It is acted upon by a force directed away from the centre of the earth which counter -balances the gravitational pull.
- d)It is an accelerated motion.
Correct answer is option 'C'. Can you explain this answer?
Consider a satellite going round the earth in a circular orbit. Which of the following statements is wrong ?
a)
It is a freely falling body
b)
It is moving with constant speed
c)
It is acted upon by a force directed away from the centre of the earth which counter -balances the gravitational pull.
d)
It is an accelerated motion.
|
|
Adarsh Mohora answered |
Speed can be constant but velocity may not be and thus acceleration
force of gravity pulls the satellite towards earth
and a centripetal force produces an acceleration to keep the satellite in their orbits
hence option c)
force of gravity pulls the satellite towards earth
and a centripetal force produces an acceleration to keep the satellite in their orbits
hence option c)
The magnitude of gravitational force between the earth and 10 kg body is:- a)98 N
- b)90 N
- c)9.8 N
- d)100 N
Correct answer is option 'A'. Can you explain this answer?
The magnitude of gravitational force between the earth and 10 kg body is:
a)
98 N
b)
90 N
c)
9.8 N
d)
100 N
|
Achal Chinavalkar answered |
Gravity of earth is 9.8 N acceleration due to gravity is also 9.8 N gravitational force is nothing but the force applied by earth Therefore, f = m*a f,= 10*9.8 f= 98 N
A geostationary satellite- a)Moves faster than the near earth satellite
- b)Has a time period less that of a near earth satellite
- c)Revolves about the polar axis
- d)Is stationary in space
Correct answer is option 'C'. Can you explain this answer?
A geostationary satellite
a)
Moves faster than the near earth satellite
b)
Has a time period less that of a near earth satellite
c)
Revolves about the polar axis
d)
Is stationary in space
|
|
Vikram Khanna answered |
A geostationary satellite revolves around the earth with the same angular velocity and in the same sense as done by the earth about its own axis, i.e. west-east direction. A polar satellite revolves around the earth's pole in north-south direction.
A glass cuboidal has dimensions 10gm × 10 cm × 4cm. it is kept with its perfect face (10 cm × 10 cm) in contact with the table. if is lifted and allowed to rest on the table with its smaller surface (10 cm × 4 cm) in contact with the table the pressure exerted will- a)remain unchanged
- b)decrease
- c)increase
- d)may increase or decrease depending on the shape of table.
Correct answer is option 'C'. Can you explain this answer?
A glass cuboidal has dimensions 10gm × 10 cm × 4cm. it is kept with its perfect face (10 cm × 10 cm) in contact with the table. if is lifted and allowed to rest on the table with its smaller surface (10 cm × 4 cm) in contact with the table the pressure exerted will
a)
remain unchanged
b)
decrease
c)
increase
d)
may increase or decrease depending on the shape of table.
|
|
Ritu Agarwal answered |
Answer:
The buoyant force or upthrust is the force exerted by a fluid (liquid or gas) on an object submerged or floating in it. It is the force that opposes the weight of the object and acts in the upward direction. According to Archimedes' principle, an object will float if the upthrust acting on it is equal to or greater than its weight.
Weight of an Object:
The weight of an object is the force exerted on it due to gravity. It depends on the mass of the object and the acceleration due to gravity. Weight is measured in newtons (N).
Upthrust:
Upthrust is the force exerted by a fluid on an object immersed in it. It is equal to the weight of the fluid displaced by the object. Upthrust acts in the opposite direction to the force of gravity.
Equilibrium:
When the weight of an object is equal to the upthrust acting on it, the object is in a state of equilibrium. In this state, there is no net force acting on the object, and it remains at rest or moves with a constant velocity.
Float:
If the weight of an object is less than the upthrust acting on it, the object will float. This means that the upthrust is greater than the weight, causing the object to rise and remain partially or completely submerged in the fluid. The object will displace an amount of fluid equal to its own weight.
Sink:
If the weight of an object is greater than the upthrust acting on it, the object will sink. This means that the weight is greater than the upthrust, causing the object to descend and be fully submerged in the fluid. The object will displace an amount of fluid less than its own weight.
Therefore, if the weight of an object is equal to or less than the upthrust acting on it, the object will float. The upthrust will be greater than or equal to the weight, allowing the object to remain partially or completely submerged in the fluid.
The buoyant force or upthrust is the force exerted by a fluid (liquid or gas) on an object submerged or floating in it. It is the force that opposes the weight of the object and acts in the upward direction. According to Archimedes' principle, an object will float if the upthrust acting on it is equal to or greater than its weight.
Weight of an Object:
The weight of an object is the force exerted on it due to gravity. It depends on the mass of the object and the acceleration due to gravity. Weight is measured in newtons (N).
Upthrust:
Upthrust is the force exerted by a fluid on an object immersed in it. It is equal to the weight of the fluid displaced by the object. Upthrust acts in the opposite direction to the force of gravity.
Equilibrium:
When the weight of an object is equal to the upthrust acting on it, the object is in a state of equilibrium. In this state, there is no net force acting on the object, and it remains at rest or moves with a constant velocity.
Float:
If the weight of an object is less than the upthrust acting on it, the object will float. This means that the upthrust is greater than the weight, causing the object to rise and remain partially or completely submerged in the fluid. The object will displace an amount of fluid equal to its own weight.
Sink:
If the weight of an object is greater than the upthrust acting on it, the object will sink. This means that the weight is greater than the upthrust, causing the object to descend and be fully submerged in the fluid. The object will displace an amount of fluid less than its own weight.
Therefore, if the weight of an object is equal to or less than the upthrust acting on it, the object will float. The upthrust will be greater than or equal to the weight, allowing the object to remain partially or completely submerged in the fluid.
The density of copper is 9 g/cm3. Then the volume of 90 g copper is- a)90 cm3
- b)9 cm3
- c)810 cm3
- d)10 cm3
Correct answer is option 'D'. Can you explain this answer?
The density of copper is 9 g/cm3. Then the volume of 90 g copper is
a)
90 cm3
b)
9 cm3
c)
810 cm3
d)
10 cm3
|
|
Hansa Sharma answered |
Density of copper = 9 gm/cm^3
Mass of copper = 90 g
We know; Density = mass / volume
⇒ volume = mass / density
⇒ 90 / 9
⇒ Volume = 10 cm3
Mass of copper = 90 g
We know; Density = mass / volume
⇒ volume = mass / density
⇒ 90 / 9
⇒ Volume = 10 cm3
The mass of the Jupiter is 1.9 × 1027 kg and that of the sun is 1.99 × 1038 kg. The mean distance of theJupiter from the sun is 7.8 × 1011 m. Speed of the Jupiter is (assuming that Jupiter moves in a circular orbitaround the sun)- a)1.304 × 104 m/sec
- b)13.04 × 104 m/sec
- c)1.304 × 106 m/sec
- d)1.304 × 102 m/sec
Correct answer is option 'A'. Can you explain this answer?
The mass of the Jupiter is 1.9 × 1027 kg and that of the sun is 1.99 × 1038 kg. The mean distance of the
Jupiter from the sun is 7.8 × 1011 m. Speed of the Jupiter is (assuming that Jupiter moves in a circular orbit
around the sun)
a)
1.304 × 104 m/sec
b)
13.04 × 104 m/sec
c)
1.304 × 106 m/sec
d)
1.304 × 102 m/sec
|
|
Hansa Sharma answered |
F = GMm / r²
= 6.67×10-¹¹ × (1.99×10³⁰) × (1.9×10²⁷) / (7.8×10¹¹)²
= 4.14×10²³ N
Now let its speed of jupiter be v, then
F = mv² / R
⇒ v =√(FR / m)
=√{(7.8×10¹¹)×(4.10×10²³) / (1.9×10²⁷)}
= 1.304×10⁴ m/sec
= 6.67×10-¹¹ × (1.99×10³⁰) × (1.9×10²⁷) / (7.8×10¹¹)²
= 4.14×10²³ N
Now let its speed of jupiter be v, then
F = mv² / R
⇒ v =√(FR / m)
=√{(7.8×10¹¹)×(4.10×10²³) / (1.9×10²⁷)}
= 1.304×10⁴ m/sec
The S. I unit of G is- a)Nkg2/m2
- b)Nm2/kg2
- c)N2m/kg
- d)Nm/kg2
Correct answer is option 'B'. Can you explain this answer?
The S. I unit of G is
a)
Nkg2/m2
b)
Nm2/kg2
c)
N2m/kg
d)
Nm/kg2
|
Abhishek Jain answered |
Universal gravitational constant is represented by ‘G’. S.I. unit of universal gravitational constant is Nm2/Kg2. As G = Fxr2/Mm.
A man throws a ball with a velocity of 20m/s. After what time will the ball come back to his hands? (Take g =10m/s2)- a)8 s
- b)2 s
- c)3 s
- d)4 s
Correct answer is option 'D'. Can you explain this answer?
A man throws a ball with a velocity of 20m/s. After what time will the ball come back to his hands? (Take g =10m/s2)
a)
8 s
b)
2 s
c)
3 s
d)
4 s
|
Ayush Kumar answered |
T1=(0-20)\-10
=2
t2 will be equal to t1
Total time=4 seconds
=2
t2 will be equal to t1
Total time=4 seconds
The force of gravitation between two bodies varies with r as:- a)r2
- b)1/r2
- c)r
- d)1/r
Correct answer is option 'B'. Can you explain this answer?
The force of gravitation between two bodies varies with r as:
a)
r2
b)
1/r2
c)
r
d)
1/r
|
|
Arvind Singh answered |
Force of gravitation is inversely proportional to square of distance 1/r^2
SI unit of G is- a)N2–m2/kg
- b)N–m2/kg
- c)N–m/kg
- d)N -m2/kg2
Correct answer is option 'D'. Can you explain this answer?
SI unit of G is
a)
N2–m2/kg
b)
N–m2/kg
c)
N–m/kg
d)
N -m2/kg2
|
|
Vikas Kapoor answered |
In SI units, G has the value 6.67 × 10-11 Newtons kg-2 m2. The direction of the force is in a straight line between the two bodies and is attractive. Thus, an apple falls from a tree because it feels the gravitational force of the Earth and is therefore subject to “gravity”.
Weight of an object is highest at- a)Center of earth
- b)Poles
- c)Above the earth’s surface
- d)Equator
Correct answer is option 'B'. Can you explain this answer?
Weight of an object is highest at
a)
Center of earth
b)
Poles
c)
Above the earth’s surface
d)
Equator
|
|
Sarita Reddy answered |
Earth is not a perfect sphere. Its radius at equator is greater than poles. Acceleration due to gravity is inversely proportional to the square of its radius. So, the acceleration due to gravity is greatest at poles. Hence, from relation, W = mg, it is clear that weight is highest at the poles.
The SI unit of pressure is- a)N
- b)N m-1
- c)Pa
- d)N m2
Correct answer is option 'C'. Can you explain this answer?
The SI unit of pressure is
a)
N
b)
N m-1
c)
Pa
d)
N m2
|
|
Akshita Jaswal answered |
Pressure=Thrust/Area
S.I unit of pressure is Pascal (Pa)
S.I unit of pressure is Pascal (Pa)
Two objects of different masses are dropped freely from a height near the surface of earth they have
A Different velocities at any instant
B Same velocities at any instant
C Different accelerations
D Same acceleration - a)(b) and (c) are correct
- b)(b) and (d) are correct
- c)(a), (b) and (c) are correct
- d)All of these
Correct answer is option 'B'. Can you explain this answer?
Two objects of different masses are dropped freely from a height near the surface of earth they have
A Different velocities at any instant
B Same velocities at any instant
C Different accelerations
D Same acceleration
A Different velocities at any instant
B Same velocities at any instant
C Different accelerations
D Same acceleration
a)
(b) and (c) are correct
b)
(b) and (d) are correct
c)
(a), (b) and (c) are correct
d)
All of these
|
aman chopra answered |
Acceleration doesn't depend on the masses of object and acceleration is same at any part of planet
Which of the following is an application of Earth’s gravitation
A. It holds atmosphere around our globe
B. It holds us firmly on the surface of the Earth
C. It is responsible for motion of moon
D. It is responsible for sea tides due to the moon - 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 'D'. Can you explain this answer?
Which of the following is an application of Earth’s gravitation
A. It holds atmosphere around our globe
B. It holds us firmly on the surface of the Earth
C. It is responsible for motion of moon
D. It is responsible for sea tides due to the moon
A. It holds atmosphere around our globe
B. It holds us firmly on the surface of the Earth
C. It is responsible for motion of moon
D. It is responsible for sea tides due to the moon
a)
(a), (b) and (c) are correct
b)
(a) and (b) are correct
c)
(b) and (c) are correct
d)
All of these
|
|
Abhishek Phogat answered |
All are correct...
In which of the following pressure is increased
A. Strap of bag is made wider
B. Knife with sharp edge
C. Shoes with flat sole
D. Nail with finely pointed tip - a)(b) and (c) are correct
- b)(a), (b) and (c) are correct
- c)(b) and (d) are correct
- d)All of these
Correct answer is option 'C'. Can you explain this answer?
In which of the following pressure is increased
A. Strap of bag is made wider
B. Knife with sharp edge
C. Shoes with flat sole
D. Nail with finely pointed tip
A. Strap of bag is made wider
B. Knife with sharp edge
C. Shoes with flat sole
D. Nail with finely pointed tip
a)
(b) and (c) are correct
b)
(a), (b) and (c) are correct
c)
(b) and (d) are correct
d)
All of these
|
Ravi Chandran answered |
Pressure is inversely proportional to the area. When force acting area is greatly reduced like fine point of knife or nail, pressure acting on that area will be much higher than same force applied over larger area.
An object weighing 5 N in air, weighs 4.5 N a liquid. The buoyant force experienced by the object is - a)(5 + 4.5) N
- b)4.5/5 N
- c)5/4.5 N
- d)0.5 N
Correct answer is 'D'. Can you explain this answer?
An object weighing 5 N in air, weighs 4.5 N a liquid. The buoyant force experienced by the object is
a)
(5 + 4.5) N
b)
4.5/5 N
c)
5/4.5 N
d)
0.5 N
|
|
Anita Menon answered |
The buoyant force experienced by the object is:- The buoyant force is in opposite direction to the weight of the object. Hence, if the object weighs 4.5 N in liquid then 0.5 N buoyant force will act on the object.
A packet of 400 g and volume 200 cm3 is put in a water tank. The relative density of packet is- a)200
- b)2
- c)4
- d)400
Correct answer is option 'B'. Can you explain this answer?
A packet of 400 g and volume 200 cm3 is put in a water tank. The relative density of packet is
a)
200
b)
2
c)
4
d)
400
|
Ayantika Patra answered |
The density of the packet is 400/200 g/cm³= 2 g/cm³
we know relative density = the density of the matter/the density of water at 4 degree celsius
so the relative density = 2g/cm³ / 1 gm/cm³= 2 (the density of water at 4 degree celsius=1gm/cm³)
the correct option is (b).
we know relative density = the density of the matter/the density of water at 4 degree celsius
so the relative density = 2g/cm³ / 1 gm/cm³= 2 (the density of water at 4 degree celsius=1gm/cm³)
the correct option is (b).
The value of acceleration due to gravity at the poles- a)Is more than at the equator
- b)Same as at the equator
- c)Is less than at the equator
- d)zero
Correct answer is option 'A'. Can you explain this answer?
The value of acceleration due to gravity at the poles
a)
Is more than at the equator
b)
Same as at the equator
c)
Is less than at the equator
d)
zero
|
|
Arvind Singh answered |
In combination, the equatorial bulge and the effects of the surface centrifugal force due to rotation mean that sea-level effective gravity increases from about 9.780 m/s2 at the Equator to about 9.832 m/s2 at the poles, so an object will weigh about 0.5% more at the poles than at the Equator.
If the distance between two masses be doubled, then the force between them will become- a)1/4 times
- b)4 times
- c)1/2 times
- d)2 times
Correct answer is option 'A'. Can you explain this answer?
If the distance between two masses be doubled, then the force between them will become
a)
1/4 times
b)
4 times
c)
1/2 times
d)
2 times
|
Daksh Shroty answered |
Yes, by coulombs law
where force is inversely proportional to distance between two bodies or masses.
where force is inversely proportional to distance between two bodies or masses.
A missile is launched with a velocity less than the escape velocity. The sum of its kinetic and potential energy is- a)Positive
- b)Negative
- c)Zero
- d)May be positive or negative depending upon its initial velocity
Correct answer is option 'B'. Can you explain this answer?
A missile is launched with a velocity less than the escape velocity. The sum of its kinetic and potential energy is
a)
Positive
b)
Negative
c)
Zero
d)
May be positive or negative depending upon its initial velocity
|
|
Ananya Sharma answered |
Kinetic energy would be obvious = 0.5mv^2
and the potential Energy would be= -Gm/r^2
Now total energy = 0.5mv^2 – Gm/r^2 hence would be negative as r approaches infinity.
For a given applied thrust, pressure exerted on a surface by a sharp pin is- a)more than the pressure exerted by a blunt pin.
- b)less than the pressure exerted by a blunt pin.
- c)equal to the pressure exerted by a blunt pin.
- d)either less or equal to the pressure exerted by a blunt pin.
Correct answer is option 'A'. Can you explain this answer?
For a given applied thrust, pressure exerted on a surface by a sharp pin is
a)
more than the pressure exerted by a blunt pin.
b)
less than the pressure exerted by a blunt pin.
c)
equal to the pressure exerted by a blunt pin.
d)
either less or equal to the pressure exerted by a blunt pin.
|
|
Swati Verma answered |
Pressure exerted by a sharp needle on a surface is more than the pressure exerted by a blunt needle.
The same body is immersed in two liquids A and B in succession. The extent to which the body sinks in liquid B is less then in liquid A. What are the conclusions that could be derived from such an observation- a)The denisty of liquid A is more then B
- b)The denisty of liquid B is more then A
- c)The density of solid is less then the liquid in both
- d)No such conclusion can be made
Correct answer is option 'B'. Can you explain this answer?
The same body is immersed in two liquids A and B in succession. The extent to which the body sinks in liquid B is less then in liquid A. What are the conclusions that could be derived from such an observation
a)
The denisty of liquid A is more then B
b)
The denisty of liquid B is more then A
c)
The density of solid is less then the liquid in both
d)
No such conclusion can be made
|
Rohit Verma answered |
The density of liquid B is more than the liquid A as more upthrust is exerted on the body in liquid B and hence it sinks less.
The sea water is denser than fresh water due to
- a)Mixing of sand
- b)Stagnation
- c)Mixing of salts
- d)Evaporation
Correct answer is option 'C'. Can you explain this answer?
The sea water is denser than fresh water due to
a)
Mixing of sand
b)
Stagnation
c)
Mixing of salts
d)
Evaporation
|
Kamna Science Academy answered |
Density is defined as the mass per unit volume. In seawater, the salts are dissolved in water resulting in an increase in their mass per unit volume. Hence, seawater is denser than freshwater because of the dissolved salts in seawater, its density increases.
Why does an iron nail sink in water while a cork floats, despite both having the same mass?- a)The cork has a higher density than the nail
- b)The nail displaces more water than the cork
- c)The nail has a greater volume of displaced water compared to the cork
- d)The density of the nail is greater than that of the water
Correct answer is option 'D'. Can you explain this answer?
a)
The cork has a higher density than the nail
b)
The nail displaces more water than the cork
c)
The nail has a greater volume of displaced water compared to the cork
d)
The density of the nail is greater than that of the water
|
Tanmay Vijayvargiya answered |
Correct Answer is d
As we know that , A object floats when it's density is less then the Density of Water (i.e 1 g/cm³ or 1 kg / m³) and A object sink when it's density is greater then Density of Water.
As we know that , A object floats when it's density is less then the Density of Water (i.e 1 g/cm³ or 1 kg / m³) and A object sink when it's density is greater then Density of Water.
Gravitational force which acts on 1 kg is- a)9.8 N
- b)1/9.8 N
- c)980 N
- d)none of these
Correct answer is option 'A'. Can you explain this answer?
Gravitational force which acts on 1 kg is
a)
9.8 N
b)
1/9.8 N
c)
980 N
d)
none of these
|
|
Bethany Fernandes answered |
To covert kg to N , we have to multiply the kg value by 9.8 . So 1x9.8=9.8. hence the answer A is correct
If the density of the object placed in a liquid is equal to the density of the liquid, the object will:- a)Float half immersed
- b)Float wholly immersed
- c)Float completely above the liquid
- d)Sink
Correct answer is option 'A'. Can you explain this answer?
If the density of the object placed in a liquid is equal to the density of the liquid, the object will:
a)
Float half immersed
b)
Float wholly immersed
c)
Float completely above the liquid
d)
Sink
|
|
Arvind Singh answered |
The body will sink half way or in other words it will float half immersed in liquid.
Practice Test/Quiz or MCQ (Multiple Choice Questions) with Solutions of Chapter "Gravitation" are available for CBSE Class 9 Science and have been compiled as per the syllabus of CBSE Class 9 Science Q. If a rock is brought from the surface of the moon,- a)Its mass will change
- b)Its weight will change but not mass
- c)Both mass and weight will change
- d)Its mass and weight both will remain same
Correct answer is option 'B'. Can you explain this answer?
Practice Test/Quiz or MCQ (Multiple Choice Questions) with Solutions of Chapter "Gravitation" are available for CBSE Class 9 Science and have been compiled as per the syllabus of CBSE Class 9 Science
Q. If a rock is brought from the surface of the moon,
a)
Its mass will change
b)
Its weight will change but not mass
c)
Both mass and weight will change
d)
Its mass and weight both will remain same
|
Sameer Singh answered |
Becuse weight is just a force which may vari due the less mass of moon but mass is a quantiy of matter contained my any object ..thus it is
If we want to determine the volume of a solid by immersing it in water, the solid should be- a)heavier than water and insoluble in it
- b)lighter than water
- c)heavier than water
- d)insoluble in water
Correct answer is option 'A'. Can you explain this answer?
If we want to determine the volume of a solid by immersing it in water, the solid should be
a)
heavier than water and insoluble in it
b)
lighter than water
c)
heavier than water
d)
insoluble in water
|
Jyoti Kapoor answered |
It should be heavier than water and insoluble in it, so that it sinks and displaces the water and also it does not mix in the water.
How does the pressure exerted by a nail change when it is compared to a flat surface?- a)It remains the same
- b)It decreases
- c)It increases
- d)It fluctuates
Correct answer is option 'C'. Can you explain this answer?
a)
It remains the same
b)
It decreases
c)
It increases
d)
It fluctuates
|
|
EduRev Class 9 answered |
The pressure exerted by a nail is greater compared to a flat surface due to its smaller tip area. The same force is concentrated on a smaller area in the case of the nail, resulting in a higher pressure. This higher pressure is what allows the nail to penetrate surfaces more easily.
SI unit of g is- a)m2/s
- b)s/m2
- c)m/s2
- d)m/s
Correct answer is option 'C'. Can you explain this answer?
SI unit of g is
a)
m2/s
b)
s/m2
c)
m/s2
d)
m/s
|
Garima Desai answered |
SI unit of g is m/s2
Explanation:
- Definition of g: g is the acceleration due to gravity, which is the force that pulls objects towards the center of the earth.
- SI unit of acceleration is m/s2, which represents the change in velocity per unit time.
- Therefore, the SI unit of g is also m/s2.
- This unit is commonly used in physics and engineering to describe the acceleration of objects under the influence of gravity.
- Other units of acceleration include km/h2, cm/s2, and ft/s2, but these are not part of the SI system.
Explanation:
- Definition of g: g is the acceleration due to gravity, which is the force that pulls objects towards the center of the earth.
- SI unit of acceleration is m/s2, which represents the change in velocity per unit time.
- Therefore, the SI unit of g is also m/s2.
- This unit is commonly used in physics and engineering to describe the acceleration of objects under the influence of gravity.
- Other units of acceleration include km/h2, cm/s2, and ft/s2, but these are not part of the SI system.
Weight- a)Is a vector quantity
- b)Of a body in interplanetary space is maximum
- c)Increases when the bodies go up
- d)None of these
Correct answer is option 'A'. Can you explain this answer?
Weight
a)
Is a vector quantity
b)
Of a body in interplanetary space is maximum
c)
Increases when the bodies go up
d)
None of these
|
|
Radha Iyer answered |
Weight is a fundamental concept in physics that refers to the force exerted on an object due to gravity. Here is a detailed explanation of the given statement:
Weight is the force experienced by an object due to the gravitational pull of the Earth or any other celestial body. It is a vector quantity because it has both magnitude and direction. The direction of the weight vector is always towards the center of the celestial body.
-
- Weight is a vector quantity because it has both magnitude and direction. The magnitude of weight is equal to the product of the mass of the object and the acceleration due to gravity. The direction of weight is always towards the center of the celestial body.
-
- Weight is directly proportional to the mass of the object. In interplanetary space, where the gravitational field is weak or negligible, the weight of a body would be much less compared to its weight on Earth. Therefore, the weight of a body in interplanetary space is not maximum.
-
- As bodies go up in the Earth's atmosphere, they move farther away from the center of the Earth. The distance between the body and the center of the Earth increases, which leads to a decrease in the acceleration due to gravity. Consequently, the weight of the body decreases as it goes up, rather than increasing.
-
- The correct answer is not "D: None of these" because option A, which states that weight is a vector quantity, is correct.
Weight:
Weight is the force experienced by an object due to the gravitational pull of the Earth or any other celestial body. It is a vector quantity because it has both magnitude and direction. The direction of the weight vector is always towards the center of the celestial body.
Explanation of the given options:
-
A: Is a vector quantity:
- Weight is a vector quantity because it has both magnitude and direction. The magnitude of weight is equal to the product of the mass of the object and the acceleration due to gravity. The direction of weight is always towards the center of the celestial body.
-
B: Of a body in interplanetary space is maximum:
- Weight is directly proportional to the mass of the object. In interplanetary space, where the gravitational field is weak or negligible, the weight of a body would be much less compared to its weight on Earth. Therefore, the weight of a body in interplanetary space is not maximum.
-
C: Increases when the bodies go up:
- As bodies go up in the Earth's atmosphere, they move farther away from the center of the Earth. The distance between the body and the center of the Earth increases, which leads to a decrease in the acceleration due to gravity. Consequently, the weight of the body decreases as it goes up, rather than increasing.
-
D: None of these:
- The correct answer is not "D: None of these" because option A, which states that weight is a vector quantity, is correct.
The value of g near the earth's surface is- a)8.9 m/s2
- b)8.9 m/s
- c)9.8 m/s2
- d)9.8 m/s
Correct answer is option 'C'. Can you explain this answer?
The value of g near the earth's surface is
a)
8.9 m/s2
b)
8.9 m/s
c)
9.8 m/s2
d)
9.8 m/s
|
Rajesh Yadav answered |
Explanation:
Gravitational Acceleration:
- The value of gravitational acceleration, denoted as 'g', near the Earth's surface is approximately 9.8 m/s^2.
- This value represents the acceleration experienced by an object due to the Earth's gravitational pull.
Acceleration Due to Gravity:
- The acceleration due to gravity is the acceleration that an object experiences when it is in free fall near the Earth's surface.
- It is approximately 9.8 m/s^2, which means that every second an object in free fall near the Earth's surface will increase its velocity by 9.8 m/s.
Variation in g:
- The value of g can vary slightly depending on the location on Earth, altitude, and other factors.
- However, for most practical purposes, a value of 9.8 m/s^2 is commonly used as the standard value of g near the Earth's surface.
Conclusion:
- Therefore, the correct value of g near the Earth's surface is 9.8 m/s^2, making option 'C' the correct answer.
Chapter doubts & questions for Gravitation & Floatation - Physics for Grade 9 2025 is part of Grade 9 exam preparation. The chapters have been prepared according to the Grade 9 exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Grade 9 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
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Physics for Grade 9
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