Please refer to Gravitation MCQ Questions Class 9 Science below. These MCQ questions for Class 9 Science with answers have been designed as per the latest NCERT, CBSE books, and syllabus issued for the current academic year. These objective questions for Gravitation will help you to prepare for the exams and get more marks.

## Gravitation MCQ Questions Class 9 Science

Please see solved MCQ Questions for Gravitation in Class 9 Science. All questions and answers have been prepared by expert faculty of standard 9 based on the latest examination guidelines.

### MCQ Questions Class 9 Science Gravitation

**Question. The mass of the earth is 81 times that of the moon and the radius of the earth is 3.5 times that of the moon. The ratio of the acceleration due to gravity at the surface of the moon to that at the surface of the earth is **

(a) 0.15

(b) 0.04

(c) 1

(d) 6

## Answer

A

**Question. A spherical planet far out in space has a mass M _{0} and diameter D_{0} . A particle of mass m falling freely near the surface of this planet will experience an acceleration due to gravity which is equal to**

(a) GM

_{0 }/ D

_{0}

(b) 4mGM

_{0}/ D

^{2}

_{0}

(c) 4GM

_{0}/ D

^{2}

_{0}

(d) GmM

_{0}/ D

^{2}

_{0 }

## Answer

C

**Question. Gravitational mass is proportional to gravitational**

(a) Field

(b) Force

(c) Intensity

(d) All of these

## Answer

D

**Question. The gravitational force between two point masses m _{1} and m_{2} at separation r is given by F = k m_{1}m_{2} / r_{2}**

The constant k

(a) Depends on system of units only

(b) Depends on medium between masses only

(c) Depends on both (a) and (b)

(d) Is independent of both (a) and (b)

## Answer

A

**Question. The moon’s radius is 1/4 that of the earth and its mass is 1/80 times that of the earth. If g represents the acceleration due to gravity on the surface of the earth, that on the surface of the moon is **

(a) g/4

(b) g/5

(c) g/6

(d) g/8

## Answer

B

**Question. Radius of earth is around 6000 km. The weight of body at height of 6000 km from earth surface becomes**

(a) Half

(b) One-fourth

(c) One third

(d) No change

## Answer

B

**Question. Let g be the acceleration due to gravity at earth’s surface and K be the rotational kinetic energy of the earth.****Suppose the earth’s radius decreases by 2% keeping all other quantities same, then**

(a) g decreases by 2% and K decreases by 4%

(b) g decreases by 4% and K increases by 2%

(c) g increases by 4% and K increases by 4%

(d) g decreases by 4% and K increases by 4%

## Answer

C

**Question. If the radius of the earth shrinks by 1.5% (mass remaining same), then the value of acceleration due to gravity changes by **

(a) 1%

(b) 2%

(c) 3%

(d) 4%

## Answer

C

**Question. Choose the correct statement from the following : ****Weightlessness of an astronaut moving in a satellite is a situation of**

(a) Zero g

(b) No gravity

(c) Zero mass

(d) Free fall

## Answer

D

**Question. An object weights 72 N on earth. Its weight at a height of R/2 from earth is **

(a) 32 N

(b) 56 N

(c) 72 N

(d) Zero

## Answer

A

**Question. A rocket is launched with velocity 10 km/s. If radius of earth is R, then maximum height attained by it will be**

(a) 2R

(b) 3R

(c) 4R

(d) 5R

## Answer

C

**Question. If the earth rotates faster than its present speed, the weight of an object will **

(a) Increase at the equator but remain unchanged at the poles

(b) Decrease at the equator but remain unchanged at the poles

(c) Remain unchanged at the equator but decrease at the poles

(d) Remain unchanged at the equator but increase at the poles

## Answer

B

**Question. **Gravitational force is the

(a) weakest force

(b) strongest force

(c) short-range force

(d) non-central force

**Answer**

A

**Question. **The universal constant of gravitation G has the unit

(a) N

(b) m/s^{2}

(c) (N m^{2})/kg^{2}

(d) J

**Answer**

B

**Question. **Where will it be profitable to purchase one kilogram sugar?

(a) At poles

(b) At equator

(c) At 45c latitude

(d) at 40c latitude

**Answer**

B

**Question. **What is the unit of relative density?

(a) kg m^{3}

(b) kg/m^{3}

(c) per m^{3}

(d) It is unitless

**Answer**

F

**Question. **The mass of a body is increased 4 fold and mass of other body is increased 16 fold. How should the distance between them be changed to keep the same gravitational force between them?

(a) 4 times

(b) (1/4) times

(c) 8 times

(d) (1/8) times

**Answer**

C

**Question. **When you put an object on a spring balance, what do you measure?

(a) Weight

(b) Force

(c) Mass

(d) Acceleration

**Answer**

A

**Question. R is the radius of the earth and ϖ is its angular velocity and p g is the value of g at the poles. The effective value of g at the latitude λ = 60° will be equal to**

(a) g_{p} – 1/4 R^{2}ϖ

(b) g_{p} – 3/4 R^{2}ϖ

(c) g_{p} – R^{2}ϖ

(d) g_{p} + 1/4 R^{2}ϖ

## Answer

A

**Question. The depth d at which the value of acceleration due to gravity becomes 1/n times the value at the surface, is [R =radius of the earth] **

## Answer

B

**Question. At what height over the earth’s pole, the free fall acceleration decreases by one percent (assume the radius** **of earth to be 6400 km) **

(a) 32 km

(b) 80 km

(c) 1.253 km

(d) 64 km

## Answer

A

**Question. Weight of 1 kg becomes 1/6 on moon. If radius of moon is 1.768 x 10 ^{6} m , then the mass of moon will be **

(a) 1.99 x 10

^{30}kg

(b) 7.56 x 10

^{22}kg

(c) 5.98 x 10

^{24}kg

(d) 7.65 x 10

^{22}kg

## Answer

D

**Question. If mass of a body is M on the earth surface, then the mass of the same body on the moon surface is**

(a) M/6

(b) Zero

(c) M

(d) None of these

## Answer

C

**Question. The acceleration due to gravity is g at a point distant r from the centre of earth of radius R. If r < R , then**

(a) g ∝ r

(b) g ∝ r^{2}

(c) g ∝ r^{-1}

(d) g ∝ r^{-2 }

## Answer

A

**Question. As we go from the equator to the poles, the value of g **

(a) Remains the same

(b) Decreases

(c) Increases

(d) Decreases upto a latitude of 45°

## Answer

C

**Question. A body is projected vertically upwards from the surface of a planet of radius R with a velocity equal to half the escape velocity for that planet. The maximum height attained by the body is **

(a) R/3

(b) R/2

(c) R/4

(d) R/5

## Answer

A

**Question. Mass of moon is 7.34 x 10 ^{22} kg. If the acceleration due to gravity on the moon is 1.4 m / s^{2} , the radius of the moon is**

**(G = 6.667 10**

^{-11}Nm^{2}/ kg^{2})(a) 0.56 x 10

^{4}m

(b) 1.87 x 10

^{6}m

(c) 1.92 x 10

^{6}m

(d) 1.01 x 10

^{8}m

## Answer

B

**Question. What should be the velocity of earth due to rotation about its own axis so that the weight at equator become 3/5 of initial value. Radius of earth on equator is 6400 km**

(a) 7.4 10^{-4} rad / sec

(b) 6.7 10^{-4} rad / sec

(c) 7.8 10^{-4} rad / sec

(d) 8.7 10^{-4} rad / sec

## Answer

C

**Question. At what height from the ground will the value of ‘g’ be the same as that in 10 km deep mine below the surface of earth**

(a) 20 km

(b) 10 km

(c) 15 km

(d) 5 km

## Answer

A

**Question. If the mass of earth is 80 times of that of a planet and diameter is double that of planet and ‘g’ on earth is 9.8m/s ^{2} , then the value of ‘g’ on that planet is **

(a) 4.9m/s

^{2}

(b) 0.98m/s

^{2}

(c) 0.49m/s

^{2}

(d) 49m/s

^{2 }

## Answer

C

**Question. R and r are the radii of the earth and moon respectively. p _{e} and p_{m} are the densities of earth and moon respectively. The ratio of the accelerations due to gravity on the surfaces of earth and moon is **

(a) R/r p

_{e}/p

_{m}(b) r/R p

_{e}/p

_{m}

(c) r/R p

_{m}/p

_{e}

(d) R/r p

_{e}/p

_{m }

## Answer

A

**Question. There are two bodies of masses 100 kg and 10000 kg separated by a distance 1 m. At what distance from the smaller body, the intensity of gravitational field will be zero**

(a) 1/9 m

(b) 1/10 m

(c) 1/11 m

(d) 10/11 m

## Answer

C

**Question. A body of mass m kg. starts falling from a point 2R above the Earth’s surface. Its kinetic energy when it has fallen to a point ‘R’ above the Earth’s surface [R-Radius of Earth, M-Mass of Earth, G-Gravitational Constant]**

(a) 1/2 GMm/R

(b) 1/6 GMm/R

(c) 2/3 GMm/R

(d) 1/3 GMm/R

## Answer

B

**Question. What is the intensity of gravitational field of the centre of a spherical shell **

(a) Gm/r^{2}

(b) g

(c) Zero

(d) None of these

## Answer

C

**Question. Energy required to move a body of mass m from an orbit of radius 2R to 3R is**

(a) GMm/12R^{2}

(b) GMm/3R^{2}

(c) GMm/8R

(d) GMm/6R

## Answer

D

**Question. The kinetic energy needed to project a body of mass m from the earth surface (radius R) to infinity is**

(a) mgR/2

(b) 2 mgR

(c) mgR

(d) mgR/4

## Answer

C

**Question. At the surface of a certain planet, acceleration due to gravity is one-quarter of that on earth. If a brass ball is transported to this planet, then which one of the following statements is not correct**

(a) The mass of the brass ball on this planet is a quarter of its mass as measured on earth

(b) The weight of the brass ball on this planet is a quarter of the weight as measured on earth

(c) The brass ball has the same mass on the other planet as on earth

(d) The brass ball has the same volume on the other planet as on earth

## Answer

A

**Question. The gravitational potential energy of a body of mass ‘m’ at the earth’s surface -mgR _{e} . Its gravitational potential energy at a height R_{e} from the earth’s surface will be (Here e R is the radius of the earth)**

(a) -2 mgR

_{e}

(b) 2 mgR

_{e}

(c) 1/2 mgR

_{e}

(d) -1/2 mgR

_{e }

## Answer

D

**Question. A body weight W newton at the surface of the earth. Its weight at a height equal to half the radius of the earth will be**

(a) W/2

(b) 2W/3

(c) 4W/9

(d) 8W/27

## Answer

C

**Question. Acceleration due to gravity on moon is 1/6 of the acceleration due to gravity on earth. If the ratio of densities of earth (p _{e}) and moon (p_{m}) is {p_{e}/p_{m}} = 5/3 then radius of moon Rm in terms of Re will be **

(a) 5/18 R

_{e}

(b) 1/6 R

_{e}

(c) 3/18 R

_{e}

(d) 1/2√3 R

_{e }

## Answer

A

**Question. A man can jump to a height of 1.5 m on a planet A. What is the height he may be able to jump on another planet whose density and radius are, respectively, one-quarter and one-third that of planet A**

(a) 1.5 m

(b) 15 m

(c) 18 m

(d) 28 m

## Answer

C

**Question. Escape velocity of a body of 1 kg mass on a planet is 100 m/sec. Gravitational Potential energy of the body at the Planet is **

(a) – 5000 J

(b) – 1000 J

(c) – 2400 J

(d) 5000 J

## Answer

A

**Question. The acceleration due to gravity near the surface of a planet of radius R and density d is proportional to**

(a) d/R^{2}

(b) dR^{2}

(c) dR

(d) d/R

## Answer

C

**Question. At what altitude in metre will the acceleration due to gravity be 25% of that at the earth’s surface (Radius ofearth = R metre) **

(a) 1/4 R

(b) R

(c) 3/8

(d) R/2

## Answer

B

**Question. If the angular speed of the earth is doubled, the value of acceleration due to gravity (g) at the north pole**

(a) Doubles

(b) Becomes half

(c) Remains same

(d) Becomes zero

## Answer

C

**Question. A body of mass m is placed on the earth’s surface. It is taken from the earth’s surface to a height h = 3R . The change in gravitational potential energy of the body is**

(a) 2/3 mgR

(b) 3/4 mgR

(c) mgR / 2

(d) mgR / 4

## Answer

B

**Question. The acceleration of a body due to the attraction of the earth (radius R) at a distance 2 R from the surface of the earth is (g = acceleration due to gravity at the surface of the earth)**

(a) g/9

(b) g/2

(c) g/4

(d) g

## Answer

A

**Question. The diameters of two planets are in the ratio 4 : 1 and their mean densities in the ratio 1 : 2. The acceleration due to gravity on the planets will be in ratio**(a) 1 : 2

(b) 2 : 3

(c) 2 : 1

(d) 4 : 1

## Answer

C

**Question. Weight of a body of mass m decreases by 1% when it is raised to height h above the earth’s surface. If the body is taken to a depth h in a mine, change in its weight is**

(a) 2% decrease

(b) 0.5% decrease

(c) 1% increase

(d) 0.5% increase

## Answer

B

**Question. The masses of two planets are in the ratio 1 : 2. Their radii are in the ratio 1 : 2. The acceleration due to gravity on the planets are in the ratio **

(a) 1 : 2

(b) 2 : 1

(c) 3 : 5

(d) 5 : 3

## Answer

B

**Question. A body of mass m rises to height h = R/5 from the earth’s surface, where R is earth’s radius. If g is acceleration due to gravity at earth’s surface, the increase in potential energy is**

(a) mgh

(b) 4/5 mgh

(c) 5/6 mgh

(d) 6/7 mgh

## Answer

C

**Question. In a gravitational field, at a point where the gravitational potential is zero **

(a) The gravitational field is necessarily zero

(b) The gravitational field is not necessarily zero

(c) Nothing can be said definitely about the gravitational field

(d) None of these

## Answer

A

**Question. The gravitational field due to a mass distribution is E = K / x ^{3} in the x-direction. (K is a constant). Taking the gravitational potential to be zero at infinity, its value at a distance x is **

(a) K/x

(b) K/2x

(c) K / x

^{2}

(d) K / 2x

^{2}

## Answer

D

**Question. Escape velocity on a planet is e v . If radius of the planet remains same and mass becomes 4 times, the escape velocity becomes **

(a) e 4 v

(b) e 2 v

(c) e v

(d) e v21

## Answer

B

**Question. The mass of the earth is 81 times that of the moon and the radius of the earth is 3.5 times that of the moon. The ratio of the escape velocity on the surface of earth to that on the surface of moon will be**

(a) 0.2

(b) 2.57

(c) 4.81

(d) 0.39

## Answer

C

**Question. The mass and diameter of a planet have twice the value of the corresponding parameters of earth. Acceleration due to gravity on the surface of the planet is**

(a) 9.8 m / sec^{2}

(b) 4.9 m / sec^{2}

(c) 980m / sec^{2}

(d) 19.6 m / sec^{2 }

## Answer

B

**Question. Radius of orbit of satellite of earth is R. Its kinetic energy is proportional to **

(a) 1/R

(b) 1/√R

(c) R

(d) 1/R^{3/2 }

## Answer

A

**Question. In some region, the gravitational field is zero. The gravitational potential in this region **

(a) Must be variable

(b) Must be constant

(c) Cannot be zero

(d) Must be zero

## Answer

B

**Question. Acceleration due to gravity ‘g’ for a body of mass ‘m’ on earth’s surface is proportional to (Radius of earth=R,mass of earth=M) **

(a) GM / R^{2}

(b) m°

(c) mM

(d) 1 / R^{3/2 }

## Answer

A

**Question. v _{e} and v_{p} denotes the escape velocity from the earth and another planet having twice the radius and the same mean density as the earth. Then **

(a) v

_{e}= v

_{p}

(b) v

_{e}= v

_{p}/2

(c) v

_{e}= 2v

_{p}

(d) v

_{e}= v

_{p}/4

## Answer

B

**Question. The escape velocity of a sphere of mass m from earth having mass M and radius R is given by**

(a) √2GM/R

(b) 2√GM/R

(c) √2GMm/R

(d) √GM/R

## Answer

A

**Question. Assuming earth to be a sphere of a uniform density, what is the value of gravitational acceleration in a mine 100 km below the earth’s surface (Given R = 6400 km) **

(a) 2 9.66 m/s^{2}

(b) 2 7.64 m/s^{2}

(c) 5.06 m/s^{2}

(d) 2 3.10 m/s^{2 }

## Answer

A

**Question. A particle falls towards earth from infinity. It’s velocity on reaching the earth would be **

(a) Infinity

(b) √2gR

(c) 2√gR

(d) Zero

## Answer

B

**Question. Gas escapes from the surface of a planet because it acquires an escape velocity. The escape velocity will depend on which of the following factors :****I. Mass of the planet Gravitation****II. Mass of the particle escaping****III. Temperature of the planet****IV. Radius of the planet****Select the correct answer from the codes given below :**

(a) I and II

(b) II and IV

(c) I and IV

(d) I, III and IV

## Answer

C

**Question. Two planets of radii in the ratio 2 : 3 are made from the material of density in the ratio 3 : 2. Then the ratio of acceleration due to gravity g _{1} / g_{2} at the surface of the two planets will be **

(a) 1

(b) 2.25

(c) 4/9

(d) 0.12

## Answer

A

**Question. The masses and radii of the earth and moon are M _{1} , R_{1} and M_{2} , R_{2} respectively. Their centres are distance d apart. The minimum velocity with which a particle of mass m should be projected from a point midway between their centres so that it escapes to infinity is **

## Answer

A

**Question. If g is the acceleration due to gravity at the earth’s surface and r is the radius of the earth, the escape velocity for the body to escape out of earth’s gravitational field is**

(a) gr

(b) √2gr

(c) g / r

(d) r / g

## Answer

B

**Question. The escape velocity for a rocket from earth is 11.2 km/sec. Its value on a planet where acceleration due to gravity is double that on the earth and diameter of the planet is twice that of earth will be in km/sec**

(a) 11.2

(b) 5.6

(c) 22.4

(d) 53.6

## Answer

C

**Question. A body weight 500 N on the surface of the earth. How much would it weigh half way below the surface of the** **earth**

(a) 125 N

(b) 250 N

(c) 500 N

(d) 1000 N

## Answer

B

**Question. If radius of earth is R then the height ‘h’ at which value of ‘g’ becomes one-fourth is **

(a) R/4

(b) 3R/4

(c) R

(d) R/8

## Answer

C

**Question. The change in potential energy, when a body of mass m is raised to a height nR from the earth’s surface is (R = Radius of earth) **

(a) mgR n/n-1

(b) nmgR

(c) mgR n^{2}/n^{2}+ 1

(d) mgR n/n+ 1

## Answer

D

**Question. The escape velocity from the earth is about 11 km/second. The escape velocity from a planet having twice the radius and the same mean density as the earth, is**

(a) 22 km/sec

(b) 11 km/sec

(c) 5.5 km/sec

(d) 15.5 km/sec

## Answer

A

**Question. 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

## Answer

B

**Question. The angular velocity of the earth with which it has to rotate so that acceleration due to gravity on 60o latitude becomes zero is (Radius of earth = 6400 km. At the poles g = 10 ms ^{-2}) **

(a) 2.5 x 10

^{-3}rad/s

(b) 5.0 x 10

^{-1}rad/s

(c) 10 x 10

^{1}rad/ s

(d) 7.8 x 10

^{-2}rad/s

## Answer

A

**Question. The radius of the earth is 6400 km and 2 g = 10m / sec ^{2}. In order that a body of 5 kg weighs zero at the equator, the angular speed of the earth is **

(a) 1/80 radian/sec

(b) 1/400 radian/sec

(c) 1/800 radian/sec

(d) 1/1600 radian/sec

## Answer

C

**Question. The value of ‘g’ at a particular point is 2 9.8 m / s ^{2} . Suppose the earth suddenly shrinks uniformly to half its present size without losing any mass. The value of ‘g’ at the same point (assuming that the distance of the point from the centre of earth does not shrink) will now be Gravitation**

(a) 2 4.9 m / sec

^{2}

(b) 2 3.1m / sec

^{2}

(c) 2 9.8 m / sec

^{2}

(d) 2 19.6 m / sec

^{2 }

## Answer

C