# MCQs on Gravitation:

• In simple terms, gravity is the attraction between any two objects in the universe.
• Gravity can be determined by knowing the mass of bodies and the distance from one to the other.
• The stronger the gravitational field, the greater will be the weight of the body and the higher its acceleration.
• For example, on the Moon, the weight of an astronaut will be six times less than on Earth.
• The strength of a gravitational field depends on the size of the object it surrounds.
• So, the lunar force of gravity is six times lower than the earth.
• Isaac Newton first substantiated this scientifically and proved it with the help of mathematical calculations back in the 17th century.
• Gravity expresses the force that causes two bodies to be attracted to each other, and it is the same force that causes objects to fall toward the earth, and planets to rotate around the sun, and gravity is one of the four main forces in nature.
• He set his law for the expression of gravity and stipulated the existence of direct proportionality between the force of gravity and the mass of the two bodies attracted towards each other, in addition to the existence of an inverse relationship between them and the square of the distance.

### Importance of gravity:

• The sun’s gravity keeps the earth in its orbit, which helps to maintain an appropriate distance between them and thus enjoy the sun’s rays comfortably.
• Earth’s gravity preserves the atmosphere around the Earth, which is what keeps us able to breathe and live. Gravity keeps the world connected.

## MCQ On Gravitation with Answers Pdf:

1. If two unit masses are placed at a unit distance apart the force of attraction between them is equal to_____

(a) acceleration due to gravity

(b) gravitational potential

(c) universal gravitational constant

(d) gravitational field strength

2. If a person travels from the equator to the poles, he finds that the value of acceleration due to gravity (g)____

(a) decreases

(b) increases

(c) remains constant

(d) decrease up to a certain latitude becomes zero, and then increases

3. Newton’s law of gravitation is applicable in the case of _______

(a) planets and stars only

(b) point masses only

(c) big bodies only

(d) all bodies in the universe

4. If the speed of rotation of the earth about its axis ln the weight of the body at the equator will_____

(a) decrease

(b) increases

(c) remain constant

(d) sometimes increases sometimes decrease

5.  The gravitational mass of the body on the Earth is M. The inertial mass of the same body on the moon will be______

(a) zero

(b) 6M

(c) M

(d) M/6

6. The ratio of the gravitational mass and inertial mass of a body is_____

(a) 2: 1

(b) 1: 2

(c) 1: 1

(d) 1.5: 1

7.  The universal constant of gravitation_____

(a)  Has no units and dimensions as it is a constant

(b)  Its value remains constant in all systems of units

(c)  That’s not dependent upon the nature of the medium in which the bodies are placed

(d) Its a force of repulsion

8. The weight of a body at the center of the earth is____

(a) infinite

(b) zero

(C)same as that on the surface of the earth

(d) half of that on the surface of the earth

9. Where does a body has the maximum weight?

(a) at the poles

(b) in an orbiting satellite

(c) at the equator

(d) on the moon

10. Gravitational force is a mutual force. Hence it is______

(a) an action force

(b) a reaction force

(c) an action-reaction force

(d) an action force but not a reaction force

11. Choose the wrong statement from the following:

(a) weight of a body is more at the poles than that at the equator

(b) weight of a body is more on the surface of the earth than on top of Mount Everest

(c)weight of a body on the moon is less than that on the earth

(d) All the statements are correct

12. Universal gravitational constant (G) is__________

(a) the gravitational force of attraction between two bodies

(b) the gravitational force of attraction between two bodies each of unit mass.

(C) the gravitational force of attraction between two bodies separated by unit distance.

(d) the gravitational force of attraction between two bodies each of unit mass, separated from each other by a unit distance.

13. If the earth suddenly stops rotating, then the value g at the equator, will___

(a) decrease

(b) increase

(c) remain the same

(d) be zero

14. If g is the acceleration due to gravity on the surface of the earth, the gain in the potential energy of a body of mass m raised from the surface of the earth to a height equal to the radius R of the earth, is____

(a) mgR

(b) 1/2 mgR

(c) 1/4 mgR

(d) 2 mgR

15. A satellite is orbiting very close to the surface of the earth. Its periodic time depends only upon the_____

(a) mass of the earth

(b) the density of the earth

(c) mass of the satellite

(d) the radius of the earth

16. For a satellite revolving around the earth______

(a) its P.E. and K.E. are +ve and the total energy is negative

(b) its P.E. and K.E. are -ve but the total energy is positive

(c) its P.E. and total energy are negative but the K.E. is positive

(d) its P.E. and total energy are positive but its K.E. is negative

17. For a geostationary satellite, which one of the following statements is wrong?

(a) It remains at a fixed height

(b) Its period of rotation is the same as that of the earth

(c) Its direction of motion is from west to east

(d) Its orbital plane is inclined at a small angle to the axis of rotation of the earth.

18. The period of an earth satellite is 5 h. If the distance between the earth and the satellite is increased to 4 times its original value, then the new period of the satellite will be_____

(a) 20 h

(b) 30 h

(c) 40 h

(d) 80 h

19. A lift is moving down with acceleration a. A man in the lift drops a ball inside the lift. The acceleration of the ball as observed by the man in the lift and a man standing stationary on the ground are respectively_____

(a) g -a, g+a

(b) g.g

(c) g-a. g

(d) a and g

20.  A satellite going around the Earth suddenly loses height and starts moving in a lower orbit at the speed of the satellite____

(a) does not change

(b) is increased

(c) is decreased

(d) may be increases or decrease

21. All the geostationary satellites used for telecommunication have_____

(a) different orbits and positions

(b) same orbit but different positions

(c) same orbit and position

(d) different orbits but the same position

22. The value of gravitational P.E. is____

(a) always zero

(b) always positive

(c) always negative

(d) may be positive or negative

23. The geostationary rockets are generally launched in the equational plane from

(a) east to west

(b) west to east

(c) South to north

(d) north to south

24. A planet is revolving around the sun in an elliptical orbit. The sun is____

(a) at the center of the ellipse

(b) at one of the foci

(c) at one end of the major axis

(d) at one end of a minor axis

25. A body is projected vertically upwards from the surface of the earth. If it’s kinetic energy is equal to half of its minimum value required to escape from the gravitational influence, then the height up to which it rises is_____

(a) 4R

(b) 3R

(c) 2R

(d) R

26. How many times a two-stage rocket should be fired to launch a satellite in its proper orbit?

(a) one

(b) two

(c) three

(d) four

27. An artificial satellite makes 8 revolutions in 72 hours. How many revolutions a geostationary satellite will make at the same time?

(a) 1

(b) 3

(c)8

(d) 16

28. A satellite is orbiting around the earth at a mean radius of 16 times that of the geostationary orbit. What is the period of the satellite?

(a) 64 days

(b) 32 days

(c) 16 days

(d) 8 days

29. What is the correct statement regarding a satellite?

(a) A satellite cannot move in a stable orbit if its plane passes through the center of the earth

(b) Two geostationary satellites are sufficient for communication around the globe

(c) Geostationary satellites are launched in the equatorial plane and are made to move from west to east

(d) the speed of the satellite increases with an increase in the radius of the orbit

30. The astronaut in a satellite, moving in a circular orbit around the earth, experiences a feeling of weightlessness because______

(a) the gravitational force acting on the astronaut is zero.

(b) acceleration due to the gravity of the earth is zero

(c) the astronaut is in an inertial frame of reference

(d) the floor of the satellite does not produce any reaction on the astronaut

31. The plane of the circular orbit of a satellite passes through.

(a) south pole

(b) north pole

(c) the center of the earth

(d) the latitude of 60°

32. The apparent weight of a man standing in a lift is more than his real weight when the lift_____

(a) goes down with an acceleration

(b) goes down with a uniform speed

(c) goes up with a uniform acceleration

(d) goes up with a uniform speed

33. The weight of an astronaut in an artificial satellite revolving around the earth is_______

(a) equal to that on the earth

(b) less than that on the earth

(c) zero

(d) more than that on the earth

34. A communication satellite of the earth travels from_____

(a) North to the south in the polar plane

(b) East to west in the equatorial plane

(c) West to the east in the equatorial plane

(d) South to the north in the polar plane

35. If the mass of the earth remains constant but the diameter of the earth becomes two times its present value, then the weight of a person weighing 80 kg-wt, would be_____

(a) 20 kg-wt

(b) 40 kg-wt

(c) 60 kg-wt

(d) 80 kg-wt

36. A man weighs 60 kg at the earth’s surface. The radius of the earth is 6400 km. At what height above the earth’s surface, his weight becomes 30 kg?

(a) 100 km

(b) 1500 km

(c)2624 km

(d) 2900 km

37. A Satellite of the earth is revolving in a circular orbit with a uniform speed v. If the gravitational force suddenly disappears, then the satellite_____

(a) will fall down like a freely falling body

(b) will continue to move with velocity v along the original path

(c) will go outwards in the direction of the centrifugal force

(d) will move with a velocity v along the tangent to the original orbit

38. For a satellite revolving in a circular orbit around the earth, the physical quantity that remains constant is its____

(a) velocity

(b) acceleration

(c) angular momentum

(c) potential energy

39. Which one of the following statements regarding an artificial satellite is wrong?

(a) The minimum velocity that should be given to a satellite to orbit quite close to the earth is about 8 km/sec.

(b) The height of a communication satellite is about 36000 km from the earth’s surface

(c) The orbital velocity of the satellite depends upon the mass of the satellite

(d) The period of revolution of a satellite is the independent value of its mass

40. The moon is a natural satellite of_________

(a) the sun

(b) the earth

(c) Jupiter

(d) Venus

41. If the horizontal velocity given to a satellite iS greater than the critical velocity but less than the escape velocity, then the satellite will______

(a) revolve in a circular orbit

(b) will strike the earth along a parabolic path

(c) start revolving in an elliptical orbit

(d) it will disappear into the outer space

42. The radius of the circular orbit of a satellite depends upon______

(a) the escape velocity

(b) the critical velocity

(c) the velocity with which the first stage rocket is projected

(d) air resistance to the motion of the satellite

43. The name of the first communication satellite launched by India is ______

(b) Telstar

(a) Agni

(c) Insatl

(d) Apple

44. A geostationary satellite of the earth______

(a) has a period of 12 hours

(b) is stationary in space

(c) revolves from west to east in the equatorial plane

(d) revolves from east to west in the equatorial plane