# MCQs for Science Class 9 with Answers Chapter 10 Gravitation

Students of class 9 Science should refer to MCQ Questions Class 9 Science Gravitation with answers provided here which is an important chapter in Class 9 Science NCERT textbook. These Multiple Choice Questions have been prepared based on the latest CBSE and NCERT syllabus and examination guidelines for Class 9 Science. The following MCQs can help you to practice and get better marks in the upcoming class 9 Science examination

Question. The earth attracts the moon with a gravitational force of 1020 N. Then the moon attracts the earth with a gravitational force of:
(A) 10–20 N
(B) 102 N
(C) 1020 N
(D) 1010 N

C

Question. The orbits of planets around the sun are:
(A) circular
(B) parabolic
(C) elliptical
(C) straight

C

Question. When the medium between two bodies changes, force of gravitation between them :
(A) will increase
(B) will decrease
(C) will change according to the environment
(D) remains same

D

Question. S.I. unit of G is :
(A) Nm2 kg–2
(B) Nm kg–2
(C) N kg2M–2
(D) Nkg m–2

A

Question.The value of G in S.I. unit is :
(A) 6.67 × 10–9
(B) 6.67 × 10–10
(C) 6.67 × 10–11
(D) 6.67 x 10–12

C

Question. A body is thrown up with a velocity of 20 m/s. The maximum height attained by it is approximately:
(A) 80 m
(B) 60 m
(C) 40 m
(D) 20 m

D

Question. The value of universal gravitational constant:
(A) changes with change of place
(B) does not change from place to place
(C) becomes more at night
(D) becomes more during the day

B

Question. The weight of a body is 120 N on the earth. If it is taken to the moon, its weight will be about:
(A) 120 N
(B) 60 N
(C) 20 N
(D) 720 N

C

Question. The gravitational force between two bodies varies with distance r as :
(A) 1/r
(B) 1/r2
(C) r
(D) r2

B

Question. Value of G on surface of earth is 6.673 × 10–11 Nm2 kg–2, then value of G on surface of Jupiter is :
(A) 12 × 6.673 × 10–11 Nm2 kg–2
(B)126.673× 10–11 Nm2 kg–2
(C) 6.673 × 10–11 Nm2 kg–2
(D)66.673× 10–11 Nm2 kg–2

C

Question. If more force is required to bring a body into a unit acceleration, the body has
(a) less mass
(b) zero mass
(c) more mass
(d) mass is independent of force.

C

Question. The weight of a body is 120 N on the earth. If it is taken to the moon, its weight will be about
(A) 120 N
(B) 60 N
(C) 20 N
(D) 720 N

C

Question. The value of acceleration due to gravity at the Mount Everest is
(A) g
(B) > g
(C) < g
(D) zero

C

Question.  of weight of a body immersed in a liquid is
(A) equal to the weight of the liquid displaced
(B) more than the weight of the liquid displaced
(C) less than the weight of the liquid displaced
(D) zero

A

Question. The type of force that exists between two charged bodies is
(A) only gravitational
(B) only electrostatic
(C) neither (a) nor (b)
(D) both (a) and (b)

D

Question. Which of the following is correct?
(A) Weight is a scalar quantity.
(B) Weight is not a fundamental quantity.
(C) Weight does not depend on acceleration due to gravity.
(D) None of these

B

Question. Law of gravitation is applicable for:
(A) heavy bodies only
(B) medium sized bodies only
(C) small sized bodies only
(D) bodies of any size

D

Question. The mass of a planet that has a moon whose time period and orbital radius are T and R respectively can be written as
(A) 4π2R3G-1T-2
(B) 8π2R3G-1T-2
(C) 12π2R3G-1T-2
(D) 16π2R3G-1T-2

A

Question. If orbital velocity of planet is given by v = GaMbRc , then
(A) a = 1 / 3, b = 1 / 3, c = -1 / 3
(B) a =1 / 2, b = 1 / 2, c = -1 / 2
(C) a = 1 / 2, b = -1 / 2, c = 1 / 2
(D) a = 1 / 2, b = -1 / 2, c = -1 / 2

B

Question. Hubble’s law states that the velocity with which milky way is moving away from the earth is proportional to
(A) Square of the distance of the milky way from the earth
(B) Distance of milky way from the earth
(C) Mass of the milky way
(D) Product of the mass of the milky way and its distance from the earth
(E) Mass of the earth

B

Question. The condition for a uniform spherical mass m of radius r to be a black hole is [G= gravitational constant and g= acceleration due to gravity]
(A) (2Gm / r)1/2 ≤ c
(B) (2Gm / r)1/2 = c
(C) (2Gm / r)1/2 ≥ c
(D) (Gm / r) 1/2 ≥ c

C

Question. Earth is revolving around the sun if the distance of the Earth from the Sun is reduced to 1/4th of the present distance then the present day length reduced by
(A) 1/4
(B) 1/2
(C) 1/8
(D) 1/6

C

Question. Imagine a light planet revolving around a very massive star in a circular orbit of radius R with a period of revolution T. If the gravitational force of attraction between planet and star is proportional to R-5/2 , then T2  is proportional to
(A) R3
(B) R7/2
(C) R5/2
(D) R3/2

B

Question. The magnitudes of the gravitational force at distances r1 rand r2 from the centre of a uniform sphere of radius R and mass M are F1 and F2 respectively. Then

A.B

Question. A satellite S is moving in an elliptical orbit around the earth. The mass of the satellite is very small compared to the mass of earth
(A) The acceleration of S is always directed towards the centre of the earth
(B) The angular momentum of S about the centre of the earth changes in direction but its magnitude remains constant
(C) The total mechanical energy of S varies periodically with time
(D) The linear momentum of S remains constant in magnitude

A

Question. A mass M is split into two parts, m and (M–m), which are then separated by a certain distance. What ratio of m/M maximizes the gravitational force between the two parts
(A) 1/3
(B) 1/2
(C) 1/4
(D) 1/5

B

Question. Suppose the gravitational force varies inversely as the nth power of distance. Then the time period of a planet in circular orbit of radius R around the sun will be proportional to

A

Question. If the radius of the earth were to shrink by 1% its mass remaining the same, the acceleration due to gravity on the earth’s surface would
(A) Decrease by 2%
(B) Remain unchanged
(C) Increase by 2%
(D) Increase by 1%

C

Question. The radius and mass of earth are increased by 0.5%. Which of the following statements are true at the surface of the earth
(A) g will increase
(B) g will decrease
(C) Escape velocity will remain unchanged
(D) Potential energy will remain unchanged

B.C.D

Question. In order to make the effective acceleration due to gravity equal to zero at the equator, the angular velocity of rotation of the earth about its axis should be ( g = 10 ms-2 and radius of earth is 6400 kms)

B

Question. A rocket of mass M is launched vertically from the surface of the earth with an initial speed V. Assuming the radius of the earth to be R and negligible air resistance, the maximum height attained by the rocket above the surface of the earth is

C

Question. A solid sphere of uniform density and radius 4 units is located with its centre at the origin O of coordinates. Two spheres of equal radii 1 unit with their centres at A(– 2, o, o) and B(2, o, o)  respectively are taken out of the solid leaving behind spherical cavities as shown in figure
(A) The gravitational force due to this object at the origin is zero
(B) The gravitational force at the point B (2, o, o) is zero
(C) The gravitational potential is the same at all points of the circle y2 +z2 = 36
(D) The gravitational potential is the same at all points on the circle y2 + z2 = 4

A.C.D

Question. A satellite is launched into a circular orbit of radius R around the earth. A second satellite is launched into an orbit of radius (1.01)R. The period of the second satellite is larger than that of the first one by approximately
(A) 0.5%
(B) 1.0%
(C) 1.5%
(D) 3.0%

C

Question. The curves for potential energy (U) and kinetic energy (Ek) of a two particle system are shown in figure. At what points the system will be bound?

(A) Only at point D
(B) Only at point A
(C) At point D and A
(D) At points A, B and C

D

Question. If the distance between the earth and the sun becomes half its present value, the number of days in a year would have been
(A) 64.5
(B) 129
(C) 182.5
(D) 730

B

Question. A geostationary satellite orbits around the earth in a circular orbit of radius 36000 km. Then, the time period of a satellite orbiting a few hundred kilometres above the earth’s surface (REarth = 6400 km ) will approximately be
(A) 1/2 h
(B) 1 h
(C) 2 h
(D) 4 h

C

Question. When a space ship is at a distance of two earths radius from the centre of the earth, the gravitational acceleration is :
(A) 19.6 ms–2
(B) 9.8 m/s–2
(C) 4.9 m/s2
(D) 2.45 ms–2

A

Question. Assuming the earth to have a constant density, point out which of the following curves show the variation of acceleration due to gravity from the centre of earth to the points far away from the surface of earth

C

Question. The value of acceleration due to gravity (g) on earth’s surface is :
(A) 6.67 x 10–11 Nm2 kg2
(B) 8.9 m/sec2
(C) 9.8 m/sec2
(D) none of these

C

Question. The universal law of gravitation was proposed by :
(A) Copernicus
(B) Newton
(C) Galileo
(D) Archimedes

B

Question. Which of the following graphs represents the motion of a planet moving about the sun

C

Question. A heavy stone falls:
(A) faster than a light stone
(B) slower than a light stone
(C) with same acceleration as light stone
(D) none of these

C

Question. Choose the correct statement :
(A) All bodies repel each other in thenuniverse.
(B) Our earth does not behave like a magnet.
(C) Acceleration due to gravity is 8.9 ms–2
(D) All bodies fall at the same rate in vacuum.

D

Question. A stone is dropped from the roof of a building takes 4s to reach the ground. The height of the building is :
(A) 19.6m
(B) 39.2 m
(C) 156.8 m
(D) 78.4 m

D

Question. The correct graph representing the variation of total energy (Et) kinetic energy (Ek) and potential energy (U) of a satellite with its distance from the centre of earth is

C

Question. The acceleration due to gravity:
(A) has the same value everywhere in space
(B) has the same value everywhere on the earth
(C) varies with the latitude on the earth
(D) is greater on moon because it has smaller diameter

C

Question. If planet existed whose mass and radius were both half of the earth, the acceleration due to gravity at the surface would be :
(A) 19.6 m/sec2
(B) 9.8 m/s2
(C) 4.9 ms–2
(D) 2.45 m/s2

A

Question. Mass of an object is :
(A) amount of matter present in the object
(B) same as weight of an object
(C) measure of gravitational pull
(D) none of these

A

Question. A stone is dropped from the top of a tower. Its velocity after it has fallen 20 m is [Take g = 10 ms–2] :
(A) 5 ms–1
(B) 10 m s–1
(C) 15 m s–1
(D) 20 m s–1

D

Question. The weight of an object is :
(A) the quantity of matter it contains
(B) refers to its inertia
(C) same as its mass but is expressed in different units
(D) the force with which it is attracted towards the earth

D

Question. A ball is thrown vertically upwards. The acceleration due to gravity:
(A) is in the direction opposite to the direction of its motion
(B) is in the same direction as the direction of its motion
(C) increases as it comes down
(D) become zero at the highest point.

A

Question. When an apple falls from a tree:
(A) only earth attracts the apple
(B) only apple attracts the earth
(C) both the earth and the apple attract each other
(D) none attracts each other

C

Question. Force of attraction between two bodies does not depend upon :
(A) the shape of bodies
(B) the distance between their centres
(C) the magnitude of their masses
(D) the gravitational constant

A

Question. The acceleration due to gravity on the moon’s surface is:
(A) approximately equal to that near the earth’s surface
(B) approximately six times that near the earth’s surface
(C) approximately one-sixth of that near the earth’s surface
(D) slightly greater than that near the earth’s surface

C

Question. The force acting on a ball due to earth has a magnitude Fb and that acting on the earth due to the ball has a magnitude Fe Then :
(A) Fb = Fe
(B) Fb > Fe
(C) Fb < Fe
(D) Fe = 0

A

Question. The ratio of the value of g on the surface of moon to that on the earth’s surface is :
(A) 6
(B) √6
(C) 1/6
(D) √6/1

C

Question. Two iron and wooden balls identical in size are released from the same height in vacuum. The time taken by them to reach the ground are-
(A) not equal
(B) exactly equal
(C) regularly equal
(D) zero

B

Question. The value of G in year 1900 was 6.673 × 10–11 Nm2 kg–2, The value of G in the year 2007 will be :
(A) 6.673 × 10–9 Nm2 kg–2
(B) 6.673 × 10–10 Nm2 kg–2
(C) 6.673 × 10–2 Nm2 kg–2
(D) 6.673 × 10–11 Nm2 kg–2

D

Read the assertion and reason carefully to mark the correct option out of the options given below:
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Question. Assertion : There is no effect of rotation of earth on acceleration due to gravity at poles.
Reason : Rotation of earth is about polar axis.

A

Question. Assertion : A force act upon the earth revolving in a circular orbit about the sun. Hence work should be done on the earth.
Reason : The necessary centripetal force for circular motion of earth comes from the gravitational force between earth and sun.

E

Question. Assertion : The universal gravitational constant is same as acceleration due to gravity.
Reason : Gravitational constant and acceleration due to gravity have same dimensional formula.

D

Question. Assertion : The ratio of inertial mass to gravitational mass is equal to one.
Reason : The inertial mass and gravitational mass of a body are equivalent.

A

Question. Assertion : Smaller the orbit of the planet around the sun, shorter is the time it takes to complete one revolution.
Reason : According to Kepler’s third law of planetary motion, square of time period is proportional to cube of mean distance from sun.

A

Question. Assertion : Gravitational force between two particles is negligibly small compared to the electrical force.
Reason : The electrical force is experienced by charged particles only.

B

Question. Assertion : If earth suddenly stops rotating about its axis, then the value of acceleration due to gravity will become same at all the places.
Reason : The value of acceleration due to gravity is independent of rotation of earth.

C

Question. Assertion : The difference in the value of acceleration due to gravity at pole and equator is proportional to square of angular velocity of earth.
Reason : The value of acceleration due to gravity is minimum at the equator and maximum at the pole.

B

Question. Assertion : Gravitational potential of earth at every place on it is negative.
Reason : Every body on earth is bound by the attraction of earth.

A

Question. Assertion : The value of acceleration due to gravity does not depend upon mass of the body on which force is applied.
Reason : Acceleration due to gravity is a constant quantity.

C

Question. Assertion : If a pendulum is suspended in a lift and lift is falling freely, then its time period becomes infinite.
Reason : Free falling body has acceleration equal to acceleration due to gravity.