CBSE Class 11 Physics Gravitation MCQs Set A

Question: In planetary motion

a) the total angular momentum remains constant

b) the linear speed remains constant

c) neither the angular momentum nor angular speed remains constant

d) the angular speed remains constant

Answer: the total angular momentum remains constant

Question: Kepler’s second law may be stated as "under the influence of central force, in equal interval of time, position vector sweeps out equal

a) area

b) None of these

c) distance

d) dispalacement

Answer: area

Question: If the distance of earth is halved from the sun, then the no. of days in a year will be

a) 129

b) 730

c) 182.5

d) 365

Answer: 129

Question: If the earth is at one-fourth of its present distance from the sun, the duration of the year will be

a) one-eighth the present year

b) one-sixth the present year

c) one-tenth the present year

d) half the present year

Answer: one-eighth the present year

Question: Newton's universal law of gravitation applies to

a) both small and big bodies

b) only valid for solar system

c) planets only

d) small bodies only

Answer: both small and big bodies

Question: The value of G varies with

a) None of these

b) radius of the planet

c) depth below the ground

d) height above the earth's surface

Answer: None of these

Question: Force of gravitational attraction is least

a) at the equator

b) at the poles

c) at a point in between equator and any pole

d) None of these

Answer: at the equator

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 depends upon the rotation of the earth.

a) Assertion is correct, reason is incorrect

b) Assertion is incorrect, reason is correct

c) Assertion is correct, reason is correct; reason is not a correct explanation for assertion

d) Assertion is correct, reason is correct; reason is a correct explanation for assertion

Answer: Assertion is correct, reason is incorrect

Question: The height of the point vertically above the earth's surface, at which acceleration due to gravity becomes 1% of its value at the earth's surface is (Radius of the earth = R)

a) 9 R

b) 10 R

c) 20 R

d) 8 R

Answer: 9 R

Question: The speed of earth’s rotation about its axis is w. Its speed is increases to x times to make the effective acceleration due to gravity equal to zero at the equator. Then x is

a) 17

b) 34

c) 8.5

d) 1

Answer: 17

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

a) At equator

b) At 40° latitude

c) At poles

d) At 45° latitude

Answer: At equator

Question: Earth is flattened at poles, bulged at the equator. This is due to

a) the centrifugal force is more at the equator than at the poles

b) the angular velocity of spinning about its axis is more at equator

c) the angular velocity of spinning about its axis is less at equator

d) earth revolves round the sun in an elliptical orbit

Answer: the centrifugal force is more at the equator than at the poles

Question: A particle is suspended from a spring and it stretches the spring by 1 cm on the surface of earth. By how much amount the same particle will stretch the same spring at a place 800 km above the surface of earth.

a) 0.79 cm

b) 1.38 cm

c) 2.38 cm

d) 1.59 cm

Answer: 0.79 cm

Question: Average density of the earth

a) is directly proportional to g

b) is inversely proportional to g

c) does not depend on g

d) is a complex function of g

Answer: is directly proportional to g

Question: If the earth were to rotates faster than its present speed, the weight of an object will

a) decrease at the equator but remain unchanged at the poles

b) remain unchanged at the equator but decrease at the poles

c) remain unchanged at the equator but increase at the poles

d) increase at the equator but remain unchanged at the poles

Answer: decrease at the equator but remain unchanged at the poles

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) 5 km

b) 15 km

c) 10 km

d) 20 km

Answer: 5 km

Question: The ratio of radii of earth to another planet is 2/3 and the ratio of their mean densities is 4/5. If an astronaut can jump to a maximum height of 1.5 m on the earth, with the same effort, the maximum height he can jump on the planet is

a) 0.8 m

b) 0.5 m

c) 1.25 m

d) 1 m

Answer: 0.8 m

Question: Consider Earth to be a homogeneous sphere. Scientist A goes deep down in a mine and scientist B goes high up in a balloon. The gravitational field measured by

a) each decreases at different rates

b) each decreases at the same rate

c) B goes on decreasing and that by A goes on increasing

d) A goes on decreasing and that by B goes on increasing

Answer: each decreases at different rates

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

a) must be constant

b) must be zero

c) must be variable

d) cannot be zero

Answer: must be constant

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 necesarily zero

c) any value between one and infinite

d) None of these

Answer: the gravitational field is necessarily zero