## Class 11 Physics Objective Chapter – 8 Gravitation

Here we are providing NCERT Class 11 Physics Objective Chapter – 8 Gravitation Chapter Wise MCQs for board exam is very important for board exam preparation. This book explains all the concepts and topics in very simple language that the students can easily understand the complex subjects also. This NCERT Class 11 Physics MCQs Chapter – 8 Gravitation Chapter consist all important topic regarding NCERT Class 11 Physics Objective Chapter – 8 Gravitation. This book basically covers all the major and minor elements that together form a democratic government. Topics like power-sharing, federalism, democracy and diversity, political parties, consequences of democracy, challenges to democracy etc. have been discussed in the NCERT Class 11 Physics Objective Chapter – 8 Gravitation. The question papers in CBSE board exams are generally based on the latest NCERT books. Hence, students must follow the NCERT book to prepare effectively for their Class 11 Physics exam. If you want color notes then click here

Class 11 Physics Objective Chapter – 8 Gravitation

1. The radius of the earth is 6400 km and g = 10 m/s². In order that a body of 5 kg weighs zero at the equator, the angular speed of the earth is

( a )  1/80 rad /s

( b )  1/400 rad /s

( c )  1/800 rad /s

( d )  1/1600 rad /s

Ans:-(  c )

2. Newton’s law of universal gravitation force is given by

( a )  F=Gm1Gm2/r4

( b )  F=Gm1m2/r2

( c )  F=( Gm1+m2 ) /r2

( d )  F=( Gm1-m2 ) /r2

Ans:-(  b )

3. If the density of Earth is doubled keeping its radius constant then acceleration due to gravity will become (  the present value is 9.8 ms-2  )

( a )  9.8 ms-2

( b )  4.9 ms-2

( c )  19.6 ms-2

( d )  2.45 ms-2

Ans:-(  c )

4. A body weighs 500 N on the surface of the earth. How much would it weight half way below the surface of the earth?

( a )  1000 N

( b )  500 N

( c )  250 N

( d )  125 N

Ans:-(  c )

5. All planets move in an elliptical orbits with the sun situated at one of the foci, is called as

( a )  Law of areas

( b )  Law of periods

( c )  Law of orbits

( d )  Law of gravitation

Ans:-(  c )

6. The time – period of a satellite of earth is 5 hours. If the separation between the earth and the satellite is increased to 4 times the previous value, the new time – period will become

( a )  10 hours

( b )  20 hours

( c )  40 hours

( d )  80 hours

Ans:-(  c )

7. Satellites orbitting the earth have finite life and sometimes debris of satellites fall to the earth. This is because

( a )  the solar cells and batteries in satellites run out

( b )  the laws of gravitation predict a trajectory spiralling inwards

( c )  of viscous forces causing the speed of satellite and hence height to gradually decrease

( d )  of collisions with other satellites

Ans:-(  c )

8. When the planet comes nearer the sun moves

( a )  fast

( b )  slow

( c )  constant at every point

( d )  none of the above

Ans:-( a )

9. 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

Ans:- ( b )

10. What would be the duration of the year if the distance between the earth and the sun gets doubled?

( a ) 1032days

( b ) 129days

( c ) 365days

( d )  730 days

Ans:- ( a )

11.Which law describes the orbits of planets around the sun?

( a )  Newton’s law

( c )  Kepler’s law

( d )  Kirchoff’s Law

Ans:-(  c )

12. A satellite is orbiting around the Earth with a period T. If the Earth suddenly shrinks to half its radius without change in mass, the period of revolution of the satellite will be

( a )  T

( b )  T/2

( c )   T/( √2 )

( d )  2T

Ans:-(  a )

13.The correct option, if speeds of gamma rays, X-rays and microwave are Vg, Vx an Vm respectively will be.

( a )  Vg > Vx > Vm

( b )  Vg < Vx < Vm

( c )  Vg > Vx > Vm

( d )  Vg = Vx = Vm

Ans:- ( d )

14. The line which joins any planet to the sun sweeps out equal area in equal interval of time, this is called as

( a )  Law of areas

( b )  Law of periods

( c )  Law of orbits

( d )  Law of gravitation

Ans: ( a )

15. If a body of mass m is taken out from a point below the surface of earth equal to half the radius of earth, R, to a height R above the earths surface, then work done on it will be

( a )  ( 5/6 )  mgR

( b )  ( 6/7 )  mgR

( c )  ( 7/8 )  mgR

( d )  ( 8/9 )  mgR

Ans:-(  c )

16. Both the earth and the moon are subject to the gravitational force of the sun. As observed from the sun, the orbit of the moon

( a )  will be elliptical

( b )  will not be strictly elliptical because the total gravitational force on it is not central

( c )  is not elliptical but will necessarily be a closed curve

( d )  deviates considerably from being elliptical due to influence of planets other than the earth

Ans:-(  b )

17. The escape velocity of a body from the surface of the earth is v. It is given a velocity twice this velocity on the surface of the earth. What will be its velocity at infinity?

( a )  v

( b )  2v

( c )  √2v

( d )  √3v

Ans:-( d )

18. A artificial satellite moving in a circular orbit around the earth has a total ( kinetic + potential )  energy E0. Its potential energy is

( a )  2E0

( b )  E0

( c )  1.5 E0

( d )  -E0

Ans:- ( a )

19. A body is projected vertically from the surface of the earth of radius R with velocity equal to half of the escape velocity. The maximum height reached by the body is

( a )  R

( b )  R/2

( c )  R/3

( d )  R/4

Ans:- ( c )

20. The sum of kinetic and potential energy is when a missile is launched with a velocity less than the escape velocity.

( a )  0

( b )  Negative

( c )  Positive

( d )  None of the option

Ans:- ( b )

21. Two satellites of mass m, and 10m, are put in the same orbit around the sun. If T1 and T2 be their time periods, then T1/T2 =

( a )  4

( b )  1

( c )  12

( d )   14

Ans:- ( b )

22. Which of the following has minimum wavelength?

( a )  Blue light

( b )  γ-rays

( c )  infrared rays

( d )  microwave

Ans:- ( b )

23. The square of time period of revolution of a planet is proportional to the cube of the semi major axis of the ellipse traced out by the planet, this is called as

( a )  Law of areas

( b )  Law of periods

( c )  Law of orbits

( d )  Law of gravitation

Ans:- ( b )

24. At sea level, a body will have minimum weight at

( a )  pole

( b )  equator

( c )  42° south latitude

( d )  37° north latitude

Ans:- ( b )

25. Keplers second law regarding constancy of arial velocity of a planet is a consequence of the law of conservation of

( a )  energy

( b )  angular momentum

( c )  linear momentum

( d )  none of these

Ans:- ( b )

16.The escape velocity for a body projected vertically upwards from the surface of the earth is 11 km/s. If the body is projected at an angle of 450 with the vertical, the escape velocity will be

( a )  11/√2 km/s

( b )  11√2 km/s

( c )  2 km/s

( d )  11 km/s

Ans:- ( d )

27.There is no atmosphere on the moon because

( a )  it is closer to the earth

( b )  it revolves round the earth

( c )  it gets light from the sun

( d )  the escape velocity of gas molecules is less than their root mean square velocity here

Ans:- ( d )

28.If the distance between the earth and the sun doubles, what would be the duration of the year?

( a )  365 days

( b )  366 days

( c )  730 days

( d )  1032 days

Ans:- ( d )

29.A projectle is fired with a velocity less than the escape velocity. What can we say about the sum of its potential and kinetic energies?

( a )  Negative

( b )  Positive

( c )  Zero

( d )  May be +ve, -ve or zero

Ans:- ( a )

30.Which of the following has maximum penetrating power?

( b )  Microwaves

( c )  γ-rays

Ans:- ( c )

31.The time period of revolution of earth around the sun in years is

( a )  0.24

( b )  1.88

( c )  1

( d )  84

Ans:- ( c )

32.The value of g at a particular point is 9.8 m/sec² suppose the earth suddenly shrink 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 the earth does not shrink )  will become

( a )  9.8 m/sec²

( b )  4.9 m/sec²

( c )  19.6 m/sec²

( d )  2.45 m/sec²

Ans:- ( a )

33.In our solar system, the inter-planetary region has chunks of matter ( much smaller in size compared to planets )  called asteroids. They

( a )  will not move around the sun, since they have very small masses compared to the sun

( b )  will move in an irregular way because of their small masses and will drift away into outer space

( c )  will move around the sun in closed orbits but not obey Kepler’s laws

( d )  will move in orbits like planets and obey Kepler’s laws

Ans:- ( d )

34.The period of geostationary artificial satellite is

( a )  24 hours

( b )  6 hours

( c )  12 hours

( d )  48 hours

Ans:- ( a )

35.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

Ans:- ( a )

36.If the radius of the earth were to be raise by 1% its mass remaining the same, the acceleration due to gravity on the surface of the earth will

( a )  increase by 1%

( b )  decrease by 2%

( c )  decrease by 1%

( d )  increase by 2%

Ans:- ( d )

37. What would be the maximum height reached by the body if the body is projected vertically from the surface of the earth of radius R with a velocity equal to half of the escape velocity?

( a )  2+R

( b )  R

( c )  R/2

( d )  R/3

Ans:- ( d )

38.The acceleration due to gravity’ increases by 0.5% when we go from equator to poles. What will be the time period of the pendulum at the equator which beats seconds at the poles?

( a )  1.950 s

( b )  1.995 s

( c )  2.050 s

( d )  2.005 s

Ans:- ( d )

39.Which of the following is called heat radiation?

( a )  X-rays

( b )  γ-rays

( d )  Microwave

Ans:- ( c )

40.The time period of revolution of mercury around the sun in years is

( a )  1

( b )  0.24

( c )  0.615

( d )  1.88

Ans:- ( b )

41.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

Ans:- ( a )

42. Choose the wrong option.

( a )  Inertial mass is a measure of difficulty of accelerating a body by an external force whereas the gravitational mass is relevant in determining the gravitational force on it by an external mass

( b )  That the gravitational mass and inertial mass are equal is an experimental result

( c )  That the acceleration due to gravity on the earth is the same for all bodies is due to the equality of gravitational mass and inertial mass

( d )  Gravitational mass of a particle like proton can depend on the presence of neighbouring heavy objects but the inertial mass cannot

Ans:- ( d )

43.If the distance between the earth and the sun were half its present value , the number of day in a year would have been

( a )  64.5

( b )  129

( c )  182.5

( d )  730

Ans:- ( b )

44. 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

Ans:- ( a )

45.The escape velocity of projection from the earth is approximately ( R = 6400 km )

( a )  7 km/sec

( b )  112 km/sec

( c )  12.2 km/sec

( d )  1.1 km/sec

Ans:- ( c )

46.In a manned satellite, people experience no gravity and it is known as

( a )  Gravity-weight

( b )  Gravitational weight

( c )  Weightlessness

( d )  Less-weight gravity

Ans:- ( c )

47. Where will it be profitable to purchase one kilogram sugar

( a )  At equator
( b )  At 40° latitude
( c )  At poles
( d )  At 45° latitude

Ans:- ( a )

48. The satellite having the same time period of revolution as that of the earth is called———-.

( a )  Stationary satellite

( b )  Geostationary satellite

( c )  Gravitational satellite

( d )  Geo satellite

Ans:- ( b )

49. 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

Ans:- ( a )

50. 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

Ans:- ( a )