STD-IX, NCERT, CBSE BOARD, GRAVITATION, MCQs

1.  A boy is whirling a stone tied with a string in a horizontal circular path. The string breaks, the stone-

(a) will continue to move in the circular path

(b) will move along a straight line towards the centre of the circular path

(c) will move along a straight line tangential to the circular path

(d) will move along a straight line perpendicular to the circular path away from the boy

 

ANS: will move along a straight line tangential to the circular path (it is due to inertia of motion)

 

2.  Neglecting rotation of the earth, if suddenly the attractive power of the earth drops to zero, a man standing on the earth will

(a) fly up                                                                      

(b) slide along the surface

(c) move out tangentially

(d) stand unaffected

 

ANS: move out tangentially

 

3.  If suddenly the gravitational force of attraction between earth and a satellite revolving around it becomes zero, then the satellite will-

(a) continue to move in its orbit with same velocity

(b) move tangentially and escape away

(c) become stationary in its orbit

(d) move towards the Earth

 

ANS: move tangentially and escape away

 

4.  The universal law of gravitation was proposed by

(a) Copernicus

(b) Newton

(c) Galileo

(d) Archimedes

 

ANS: Newton

 

5. Newton’s law of gravitation is valid-

(a) on the earth only

(b) on the moon only

(c) in the laboratory only

(d) everywhere

 

ANS: everywhere

 

6.  Newton’s Law of gravitation:

(a) can be verified in the laboratory

(b) cannot be verified but is true

(c) is valid only on Earth

(d) is valid only in the solar system

 

ANS: can be verified in the laboratory

 

7.  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

 

ANS: bodies of any size

 

8.  Law of gravitation gives the gravitational force between-

(a) the earth and a point mass only

(b) the earth and sun only

(c) any two bodies having some mass

(d) two charged bodies only

 

ANS: any two bodies having some mass

 

9.  The type of force which exists between charged bodies is-

(a) only gravitational

(b) neither gravitational

(c) only electrical

(d) both electrical and gravitational

 

ANS: both electrical and gravitational

 

10.  The gravitational force is-

(a) the weakest force

(b) the strongest force

(c) a short-range force

(d) non-central force

 

ANS: the weakest force

 

11.  Gravitational force is a-

(a) repulsive force

(b) action at a distance force

(c) neither (a) nor (b)

(d) both (a) and (b)

 

ANS: neither (a) nor (b)

 

12.  Two particles are kept at a separation r. The gravitational force between them is proportional to-

(a) r

(b) r²

(c) 1/r

(d) 1/r²

 

ANS: 1/r²

 

13.  The universal law of gravitation is the force law also known as the-

(a) triangular law

(b) square law

(c) inverse square law

(d) parallelogram law

 

ANS: inverse square law

 

14.  Inverse square law means,

(a) ∝ r

(b) ∝ r^-1

(c) ∝ r^-2

(d) ∝ r²

 

ANS: ∝ r^-2

 

15.  The force of gravitation between two bodies does not depend on-

(a) their separation

(b) product of their masses

(c) sum of their masses

(d) gravitational constant

 

ANS: sum of their masses

 

16.  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

 

ANS: the shape of bodies

 

17.  Gravitational force (F) between earth of mass M and an object of mass m lying on the surface of the earth (radius of earth = R) is-

 

ANS: GMm/R2

 

18.  The equation of Gravitational force  is valid for-

(a) rectangular bodies

(b) circular bodies

(c) elliptical bodies

(d) spherical bodies

 

ANS: spherical bodies

 

19.  In the relation of Gravitational force, the quantity G

(a) depends on the value of g at a place

(b) is used only when earth is one of the two masses

(c) is universal constant in nature

(d) is greatest at the surface of the earth

 

ANS: is universal constant in nature

 

20.  Force of attraction between two objects each of mass 1 kg and separated by 1 m is called-

(a) gravitational potential

(b) acceleration due to gravity

(c) gravitational field

(d) universal gravitational constant

 

ANS: universal gravitational constant

 

21.  The force of gravitation between two bodies of mass 1 kg each kept at a distance of 1 m is-

(a) 6.67 N

(b) 6.67 x 10^-9 N

(c) 6.67 x 10^-7 N

(d) 6.67 x 10^-11 N

 

ANS: 6.67 x 10^-11 N

 

22.  Order of magnitude of G in S.I. unit is-

(a) 10^-11

(b) 10¹¹

(c) 10^-7

(d) 10⁷

 

ANS: 10^-11

 

23.  The universal constant of gravitation G has the SI unit-

(a) N

(b) m/s²

(c) Nm²/kg²

(d) J

 

ANS: Nm²/kg²

 

24.  The CGS unit of gravitational constant (G) is-

(a) N m² kg^-2

(b) dyne cm² kg^-2

(c) dyne cm² g^-2

(d) N cm² g^-2

 

ANS: dyne cm² g^-2

 

25.  The value of gravitational constant in CGS units is-

(a) 6.67 x 10^-11

(b) 6.67 x 10^-8

(c) 6.67 x 10^-7

(d) 6.67 x 10^-14

 

ANS: 6.67 x 10^-8

                                                             

26.  The ratio of SI unit to CGS unit of G is-

(a) 10³

(b) 10²

(c) 10^-2

(d) 10^-3

 

ANS: 10^-3

 

27.  The value of G depends on-

(a) masses of the bodies

(b) distance between the bodies

(c) both (a) and (b)

(d) None

 

ANS: none

28.  The value of G in year 1900 was 6.673 x 10^-11 Nm²kg^-2. Then the value of G in the year 2025 will be,

(a) 6.671 x 10^-11

(b) 6.673 x 10^-2

(c) 6.673 x 10^-11

(d) 6.671 x 10^-9

 

ANS: 6.673 x 10^-11

 

29.  If the value of G on the surface of earth is 6.773 x 10^-11 Nm²kg^-2, then the value of G on the planet Jupiter is,

(a) 12 x 6.773 x 10^-11 Nm²kg^-2

(b)  x 10^-11 Nm²kg^-2

(c) 6.673 x 10^-11 Nm²kg^-2

(d)   x 10^-11 Nm²kg^-2

 

ANS: 6.673 x 10^-11 Nm²kg^-2

 

30.  Which of the following statements regarding gravitational force existing between two bodies is TRUE?

(a) first body exerts attractive force on second body while second body exerts repulsive force on first body

(b) the gravitational force is zero when they are kept in vacuum

(c) force exerted by the first body on second is not equal to the force exerted by second body on first

(d) force exerted by first body on second body is equal to the force exerted by second body on first

 

ANS: force exerted by first body on second body is equal to the force exerted by second body on first

 

31.  The earth attracts the moon with a force F. The moon will attract the earth with a force

(a) F/2

(b) 2F

(c) F/4

(d) F

 

ANS: F

 

32.  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) 10²⁰ N

(c) 10² N

(d) 10¹⁰ N

 

ANS: 10²⁰ N

 

33. 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

 

ANS: both the earth and the apple attract each other

 

34.  An apple falls from a tree because of gravitational attraction between the earth and apple. If F₁ is the magnitude of force exerted by the earth on the apple and F₂ is the magnitude of force exerted by apple on earth, then

(a) F₁ is very much greater than F₂

(b) F₂ is very much greater than F₁

(c) F₁ is only a little greater than F₂

(d) F₁ and F₂ are equal

 

ANS: F₁ and F₂ are equal

 

35.  The force acting on a ball due to earth has a magnitude F_b and that acting on the earth due to the ball has a magnitude F_e, then-

(a) F_b = F_e

(b) F_b > F_e

(c) F_b < F_e

(d) F_e = 0

 

ANS: F_b = F_e

 

36.  Two masses m and M are kept at a distance r. The ratio of the force exerted on m due to M and that of M due to m is equal to-

(a) m : M

(b) M : m

(c) mr : M

(d) 1 : 1

 

ANS: 1 : 1

 

37.  Two particles of mass m₁ and m₂, approach each other due to their mutual gravitational attraction only. Then-

(a) accelerations of both the particles are equal

(b) acceleration of the particle of mass m₁ is proportional to m₁

(c) acceleration of the particle of mass m₁ is proportional to m₂

(d) acceleration of the particle of mass m₁ is inversely proportional to m₁

 

ANS: acceleration of the particle of mass m₁ is proportional to m₂

 

38.  Two objects attract each other by gravitational force F. If mass of one object is doubled, the gravitational force between these objects will be,

(a) F/2

(b) F

(c) 2F

(d) 4F

 

ANS: 2F

 

39.  Two objects attract each other by a force F. If masses of both the objects are doubled, the force between these objects will be-

(a) F/2

(b) F

(c) 2F

(d) 4F

 

ANS: 4F

 

40.  The gravitational force between two objects is F. If masses of both objects are halved without changing distance between them, then the gravitation force would become-

(a) F/4

(b) F/2

(c) F

(d) 2F

 

ANS: F/4

 

41.  The gravitational force between two iron balls is 4 N. If the distance between the balls is reduced to half, the gravitational force between the balls will be

(a) N/2

(b) 2 N

(c) 4 N

(d) 16 N

 

ANS: 16 N

 

42.  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) ¼ times

(c) 8 times

(d) 1/8 times

 

ANS: 8 times

 

43.  The gravitational force of attraction between two bodies at a certain distance is 70 N. If the distance of separation between them is doubled, then find the percentage change in force of attraction?

(a) decreases by 25%

(b) decreases by 75%

(c) increases by 50%

(d) increases by 75%

 

ANS: decreases by 75%

 

44.  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

 

ANS: remains same

 

45.  The gravitational force between two masses kept at a certain distance is x N. The same two masses are now kept in water and the distance between them are same. The gravitational force between these masses in water is y N. Then,

(a) x = y

(b) x < y

(c) x > y

(d) can’t say

 

ANS: x = y

46.  The atmosphere is held to the earth by

(a) gravity

(b) clouds

(c) wind

(d) earth’s magnetic field

 

ANS: gravity

 

47.  The gravitational effect of which of the following causes tidal waves in sea-

(a) earth

(b) moon

(c) sun

(d) none

 

ANS: moon

 

48.  Which of the following forces is responsible for the flow of water in rivers?

(a) Force of friction

(b) Gravitational force

(c) Electrostatic force

(d) Magnetic force

 

ANS: Gravitational force