1.Who proposed the universal law of gravitation?
a) Albert Einstein
b) Isaac Newton
c) Galileo Galilei
d) Johannes Kepler
Answer: b) Isaac Newton
Explanation: Newton formulated the law of universal gravitation in 1687.
2. The universal law of gravitation states that the force between two masses is:
a) Directly proportional to the sum of their masses
b) Directly proportional to the product of their masses and inversely proportional to the square of the distance between them
c) Inversely proportional to the distance between them
d) Independent of the distance
Answer: b) Directly proportional to the product of their masses and inversely proportional to the square of the distance between them
Explanation: This is the fundamental statement of Newton’s law of gravitation.
3. The universal gravitational constant (G) has the value:
a) 9.8 m/s²
b) 6.67 × 10⁻¹¹ N·m²/kg²
c) 3.14
d) 1.6 × 10⁻¹⁹ C
Answer: b) 6.67 × 10⁻¹¹ N·m²/kg²
Explanation: G is a universal constant that quantifies gravitational attraction.
4. If the distance between two masses is doubled, the gravitational force between them becomes:
a) Four times greater
b) Twice as great
c) One-fourth as much
d) One-half as much
Answer: c) One-fourth as much
Explanation: Force varies inversely as the square of the distance.
5. Gravitational force is a:
a) Vector quantity
b) Scalar quantity
c) Both scalar and vector
d) None of these
Answer: a) Vector quantity
Explanation: Force has magnitude and direction, so it’s a vector.
6. Weight of an object on the Moon is:
a) Same as on Earth
b) Less than on Earth
c) More than on Earth
d) Zero
Answer: b) Less than on Earth
Explanation: The Moon’s gravity is about 1/6th that of Earth.
7. Acceleration due to gravity on the Earth’s surface is approximately:
a) 9.8 m/s²
b) 8.9 m/s²
c) 10.5 m/s²
d) 7.2 m/s²
Answer: a) 9.8 m/s²
Explanation: This is the standard gravitational acceleration.
8. The force of gravity acts:
a) Only on Earth
b) Between any two masses anywhere in the universe
c) Only between planets
d) Only in the absence of air resistance
Answer: b) Between any two masses anywhere in the universe
Explanation: Gravity is a universal force acting between any two masses.
9. Gravitational potential at a point is:
a) Always positive
b) Always negative
c) Zero
d) Either positive or negative
Answer: b) Always negative
Explanation: Gravitational potential energy is taken as zero at infinite distance; closer points have negative potential.
10. Escape velocity from Earth is approximately:
a) 11.2 km/s
b) 9.8 km/s
c) 7.9 km/s
d) 5.4 km/s
Answer: a) 11.2 km/s
Explanation: This is the minimum speed needed to escape Earth’s gravitational field.
11. If the mass of Earth doubled and radius remained the same, acceleration due to gravity would:
a) Remain same
b) Double
c) Halve
d) Quadruple
Answer: b) Double
Explanation: 
, doubling mass doubles g.
12. Gravitational force is always:
a) Attractive
b) Repulsive
c) Attractive or repulsive depending on masses
d) Zero
Answer: a) Attractive
Explanation: Gravity always attracts masses.
13 .The shape of the Earth due to its rotation is:
a) Perfect sphere
b) Oblate spheroid
c) Prolate spheroid
d) Cubic
Answer: b) Oblate spheroid
Explanation: Rotation causes Earth to bulge at the equator.
14 . The gravitational field inside a hollow spherical shell is:
a) Same as outside
b) Zero
c) Varies linearly with distance from center
d) Infinite
Answer: b) Zero
Explanation: Gravity cancels inside a hollow shell.
15. Kepler’s first law states that the orbit of a planet is:
a) Circular
b) Elliptical with the Sun at one focus
c) Parabolic
d) Hyperbolic
Answer: b) Elliptical with the Sun at one focus
Explanation: Planets move in elliptical orbits around the Sun.
16. The time taken by a planet to complete one orbit around the Sun is called:
a) Period
b) Frequency
c) Wavelength
d) Amplitude
Answer: a) Period
Explanation: Orbital period is the time to complete one revolution.
17. The acceleration due to gravity decreases with altitude because:
a) Mass of Earth decreases
b) Distance from Earth’s center increases
c) Earth’s radius increases
d) None of these
Answer: b) Distance from Earth’s center increases
Explanation: Gravity decreases with the square of the distance from the center.
18. A satellite in a circular orbit experiences:
a) No force
b) Centripetal force provided by gravity
c) Centrifugal force only
d) Frictional force only
Answer: b) Centripetal force provided by gravity
Explanation: Gravity provides the centripetal force to keep the satellite in orbit.
19. Gravitational potential energy of an object at height h above Earth’s surface is:
a) 
b) 
c) Zero
d) 
Answer: b)
Explanation: Potential energy is negative and depends on the distance from Earth’s center.
20. The value of acceleration due to gravity at the center of the Earth is:
a) Zero
b) Maximum
c) Same as surface
d) Infinite
Answer: a) Zero
Explanation: Gravity inside the Earth decreases linearly to zero at the center.
21. The value of gravitational potential at infinite distance from Earth is:
a) Zero
b) Negative
c) Positive
d) Infinite
Answer: a) Zero
Explanation: Gravitational potential is defined as zero at infinite distance.
22. If the radius of Earth becomes double but its mass remains the same, acceleration due to gravity:
a) Remains the same
b) Halves
c) Becomes one-fourth
d) Doubles
Answer: c) Becomes one-fourth
Explanation: , doubling radius reduces gravity by 4 times.
23. The time period of a simple pendulum depends on:
a) Mass of bob
b) Length of the pendulum
c) Amplitude of oscillation
d) Gravitational acceleration
Answer: b) Length of the pendulum and d) Gravitational acceleration
Explanation: 
, mass and amplitude (small) do not affect T.
24. What is the value of escape velocity from Moon compared to Earth?
a) Same
b) Greater
c) Less
d) Zero
Answer: c) Less
Explanation: Escape velocity depends on mass and radius; Moon has less mass and radius.
25. The geostationary satellite orbits at:
a) 100 km above Earth
b) 36000 km above Earth
c) 2000 km above Earth
d) 500 km above Earth
Answer: b) 36000 km above Earth
Explanation: This altitude allows the satellite to match Earth’s rotation period.
26. Which of the following affects the gravitational force between two objects?
a) Mass of objects
b) Distance between objects
c) Medium between objects
d) Both a and b
Answer: d) Both a and b
Explanation: Force depends on mass and distance, not on the medium.
27. Gravitational force inside Earth varies with:
a) Inverse square of radius
b) Linearly with radius
c) Constant
d) Inverse radius
Answer: b) Linearly with radius
Explanation: Inside Earth, gravity decreases linearly towards the center.
28. If a planet has twice the radius and twice the mass of Earth, acceleration due to gravity on its surface is:
a) Same as Earth
b) Twice of Earth
c) Half of Earth
d) Four times Earth
Answer: a) Same as Earth
Explanation: 
— Corrected: Actually half of Earth’s gravity, so answer is c) Half of Earth. Sorry!
Correction: Answer: c) Half of Earth
29.The period of revolution of a satellite depends on:
a) Its mass
b) Radius of orbit
c) Mass of Earth
d) Both b and c
Answer: d) Both b and c
Explanation: Period depends on orbit radius and Earth’s mass, not satellite mass.
30.Which quantity remains constant for a satellite moving in an elliptical orbit?
a) Kinetic energy
b) Angular momentum
c) Potential energy
d) Speed
Answer: b) Angular momentum
Explanation: Angular momentum is conserved in central force motion.
31. Weightlessness in space is due to:
a) Absence of gravity
b) Free fall of the spacecraft
c) No air resistance
d) None of these
Answer: b) Free fall of the spacecraft
Explanation: Astronauts experience weightlessness due to continuous free fall.
32. If the gravitational force between two objects is F, and the distance between them is halved, the new force is:
a) 
b) 
c)
d)
Answer: b)
Explanation: Force varies inversely with the square of distance.
33. The formula for gravitational potential energy between two masses is:
a)
b) 
c)
d) 
Answer: a)
Explanation: Gravitational potential energy is negative and inversely proportional to distance.
34. The value of G is determined by:
a) Cavendish experiment
b) Newton’s laws
c) Kepler’s laws
d) Galileo’s experiment
Answer: a) Cavendish experiment
Explanation: Cavendish measured G using torsion balance.
35. If a satellite’s orbital speed increases, the radius of its orbit:
a) Increases
b) Decreases
c) Remains same
d) Becomes zero
Answer: b) Decreases
Explanation: Higher speed corresponds to a lower orbit radius for a circular orbit.
36. The acceleration due to gravity on a planet depends on:
a) Mass of the planet only
b) Radius of the planet only
c) Both mass and radius of the planet
d) Neither mass nor radius
Answer: c) Both mass and radius of the planet
Explanation: 
.
37. The law of gravitation is valid:
a) Only near Earth’s surface
b) Only for planets
c) Universally, for any two masses
d) Only in vacuum
Answer: c) Universally, for any two masses
Explanation: It is a universal law valid everywhere.
38. The velocity required for a satellite to remain in orbit close to Earth’s surface is called:
a) Escape velocity
b) Orbital velocity
c) Terminal velocity
d) Critical velocity
Answer: b) Orbital velocity
Explanation: Orbital velocity allows satellite to orbit Earth.
39. Kepler’s second law states that:
a) Planets move in elliptical orbits
b) Equal areas are swept in equal times
c) Square of time period proportional to cube of radius
d) None of these
Answer: b) Equal areas are swept in equal times
Explanation: This implies conservation of angular momentum.
40. The gravitational force between two objects separated by 1 m is 10 N. If their separation becomes 3 m, the force will be:
a) 
N
b) N
c) 30 N
d) 90 N
Answer: a) N
Explanation: Force scales as 
, so 
N.
41. The value of gravitational acceleration inside Earth at a distance r from center is proportional to:
a) 
b) 
c) 
d)
Answer: b)
Explanation: Inside Earth, 
varies linearly with distance from the center.
42. The gravitational force between Earth and a body of mass m is mg, where g is:
a) The same everywhere on Earth
b) The gravitational acceleration at Earth’s surface
c) Independent of height
d) Varies with mass m
Answer: b) The gravitational acceleration at Earth’s surface
Explanation: is acceleration due to gravity at Earth’s surface, so 
.
43. The gravitational potential energy of a satellite orbiting Earth is:
a) Zero
b) Positive
c) Negative
d) Infinity
Answer: c) Negative
Explanation: Potential energy in gravitational field is negative relative to zero at infinite distance.
44. The radius of geostationary orbit is about:
a) 6400 km
b) 42160 km
c) 35786 km
d) 10000 km
Answer: c) 35786 km
Explanation: Geostationary satellites orbit at about 36,000 km from Earth’s surface (~42,160 km from Earth’s center).
45. The acceleration due to gravity on the surface of a planet is . What is the acceleration at a height h above the surface?
a) 
b)
c) 
d)
Answer: a)
Explanation: Gravity decreases with square of the distance from the center.
46. If a planet’s radius decreases but its mass remains constant, its surface gravity:
a) Increases
b) Decreases
c) Remains same
d) Zero
Answer: a) Increases
Explanation: , so reducing 
increases .
47. The value of can be experimentally determined using:
a) Newton’s cradle
b) Torsion balance
c) Pendulum
d) Barometer
Answer: b) Torsion balance
Explanation: Cavendish used torsion balance to measure .
48. Which of the following does NOT affect the orbital speed of a satellite?
a) Mass of satellite
b) Mass of Earth
c) Radius of orbit
d) Gravitational constant
Answer: a) Mass of satellite
Explanation: Orbital speed depends on 
and radius, independent of satellite’s mass.
49. If Earth’s mass doubles and radius doubles, acceleration due to gravity becomes:
a) Same
b) Double
c) Half
d) Quarter
Answer: c) Half
Explanation: 
.
50. The escape velocity is independent of:
a) Mass of the planet
b) Radius of the planet
c) Mass of the escaping object
d) Gravitational constant
Answer: c) Mass of the escaping object
Explanation: Escape velocity depends only on planet’s mass and radius.
51. Kepler’s third law is mathematically expressed as:
a) 
b) 
c)
d)
Answer: a)
Explanation: Square of orbital period proportional to cube of orbital radius.
52. A satellite moving in an elliptical orbit has:
a) Constant speed
b) Variable speed
c) Constant kinetic energy
d) None of the above
Answer: b) Variable speed
Explanation: Speed changes due to conservation of angular momentum.
53. What happens to gravitational potential energy when the distance between two masses increases?
a) Increases
b) Decreases
c) Remains constant
d) Becomes zero
Answer: a) Increases (becomes less negative)
Explanation: Gravitational potential energy increases (towards zero) as separation increases.
54. The acceleration due to gravity is zero at:
a) Earth’s surface
b) Earth’s center
c) Infinite distance from Earth
d) Both b and c
Answer: d) Both b and c
Explanation: Gravity is zero at Earth’s center and infinitely far away.
55. The gravitational force between two identical spheres each of mass m and radius r when placed in contact is:
a) 
b) 
c)
d) Zero
Answer: b)
Explanation: Distance between centers = 2r when spheres are in contact.
56. Weight of an object is maximum at:
a) Equator
b) Poles
c) Anywhere on Earth
d) At the center of Earth
Answer: b) Poles
Explanation: Earth’s rotation reduces effective gravity at equator.
57. Gravitational force between two bodies is 16 N. If their masses are doubled and distance is doubled, the force becomes:
a) 16 N
b) 8 N
c) 32 N
d) 4 N
Answer: b) 8 N
Explanation: 
, new force = 
. Actually the force remains 16 N, correction here.
Correction: New force = 16 N
58. What is the work done by gravitational force on a satellite in a circular orbit?
a) Zero
b) Positive
c) Negative
d) Infinite
Answer: a) Zero
Explanation: Force is perpendicular to displacement in circular motion.
59. The velocity of satellite in low Earth orbit is approximately:
a) 7.8 km/s
b) 11.2 km/s
c) 3.5 km/s
d) 5 km/s
Answer: a) 7.8 km/s
Explanation: Orbital speed near Earth surface is ~7.8 km/s.
60. Potential at surface of Earth is:
a) 
b) 
c) Zero
d) Infinite
Answer: a)
Explanation: Gravitational potential is negative and depends on radius.
61. If the Earth were suddenly shrunk to half its radius without changing its mass, the acceleration due to gravity on its surface would:
a) Remain same
b) Double
c) Quadruple
d) Halve
Answer: c) Quadruple
Explanation: , halving increases by factor of 4.
62. In gravitational interaction, the force on the two masses is:
a) Different in magnitude and direction
b) Equal in magnitude and opposite in direction
c) Equal in magnitude and same direction
d) Zero
Answer: b) Equal in magnitude and opposite in direction
Explanation: Newton’s third law states action and reaction forces are equal and opposite.
63. The time period of satellite orbiting Earth depends on:
a) Satellite’s mass only
b) Radius of orbit only
c) Both satellite’s mass and radius
d) Neither
Answer: b) Radius of orbit only
Explanation: 
, independent of satellite mass.
64. Gravitational force is a:
a) Contact force
b) Non-contact force
c) Both
d) None
Answer: b) Non-contact force
Explanation: Gravity acts at a distance without physical contact.
65. Escape velocity is independent of:
a) Radius of planet
b) Mass of planet
c) Mass of escaping body
d) Gravitational constant
Answer: c) Mass of escaping body
Explanation: Escape velocity formula doesn’t include the object’s mass.
66. If the gravitational constant G were to increase, the acceleration due to gravity on Earth’s surface would:
a) Increase
b) Decrease
c) Remain same
d) Become zero
Answer: a) Increase
Explanation: , so increasing G increases g.
67. A satellite in a circular orbit is:
a) Accelerating
b) Moving with constant speed and no acceleration
c) Moving with uniform velocity
d) At rest
Answer: a) Accelerating
Explanation: Acceleration is centripetal, directed towards Earth’s center.
68. The energy of a satellite in orbit is:
a) Kinetic energy only
b) Potential energy only
c) Sum of kinetic and potential energy
d) Zero
Answer: c) Sum of kinetic and potential energy
Explanation: Total mechanical energy = KE + PE.
69. The net gravitational force on a mass inside a hollow spherical shell is:
a) Same as outside
b) Zero
c) Infinite
d) Equal to shell’s mass
Answer: b) Zero
Explanation: Inside a hollow shell, gravitational forces cancel out.
70. The gravitational force between two objects depends on:
a) Product of their masses
b) Square of distance between them
c) Sum of their masses
d) Difference of their masses
Answer: a) Product of their masses
Explanation: Newton’s law: 
.
71. If a satellite moves to an orbit with twice the radius, its orbital period becomes:
a) Twice
b) Four times
c) 
times
d) 
times
Answer: d) times
Explanation: 
, so 
.
72. The minimum velocity needed to keep a satellite in orbit close to Earth’s surface is:
a) Escape velocity
b) Orbital velocity
c) Terminal velocity
d) Sound velocity
Answer: b) Orbital velocity
Explanation: Orbital velocity allows the satellite to stay in orbit.
73. Gravitational potential energy is zero at:
a) Earth’s surface
b) Infinity
c) Center of Earth
d) Moon’s surface
Answer: b) Infinity
Explanation: Conventionally, potential energy is zero at infinite distance.
74. Acceleration due to gravity on the surface of the Moon is about:
a) 1.62 m/s²
b) 9.8 m/s²
c) 3.7 m/s²
d) 0 m/s²
Answer: a) 1.62 m/s²
Explanation: Moon’s gravity is about 1/6th of Earth’s.
75. Which law states the relation between force and acceleration?
a) Newton’s first law
b) Newton’s second law
c) Newton’s third law
d) Kepler’s first law
Answer: b) Newton’s second law
Explanation: 
.
76. The work done by gravity on a freely falling body is:
a) Zero
b) Negative
c) Positive
d) Infinite
Answer: c) Positive
Explanation: Gravity does work to increase the body’s kinetic energy.
77. A geostationary satellite revolves around Earth in:
a) 12 hours
b) 24 hours
c) 1 hour
d) 365 days
Answer: b) 24 hours
Explanation: It matches Earth’s rotation period.
78. The gravitational potential due to a point mass M at distance r is:
a)
b)
c)
d)
Answer: b)
Explanation: Potential is negative and inversely proportional to r.
79. When a body moves from Earth’s surface to infinity, its gravitational potential energy:
a) Increases
b) Decreases
c) Remains constant
d) Becomes negative
Answer: a) Increases
Explanation: Potential energy increases from negative to zero at infinity.
80. The magnitude of gravitational force between two objects is:
a) Proportional to the distance between them
b) Proportional to the square of the distance between them
c) Inversely proportional to the distance between them
d) Inversely proportional to the square of the distance between them
Answer: d) Inversely proportional to the square of the distance between them
Explanation: According to Newton’s law.
81. The force that keeps the planets in orbit around the Sun is:
a) Electromagnetic force
b) Nuclear force
c) Gravitational force
d) Frictional force
Answer: c) Gravitational force
Explanation: Gravity provides the centripetal force.
82. The gravitational force inside a solid sphere at a distance r from the center is:
a) Zero
b) 
c)
d) Constant
Answer: c)
Explanation: Gravity varies linearly inside the sphere.82.
83. Escape velocity from Earth is proportional to:
a) 
b)
c) 
d) 
Answer: a)
Explanation: 
.
84. A satellite moving with speed less than orbital velocity:
a) Escapes Earth
b) Falls to Earth
c) Remains in orbit
d) Moves away infinitely
Answer: b) Falls to Earth
Explanation: Insufficient speed to maintain orbit.
85. The point at which gravitational potential energy is minimum is:
a) At Earth’s surface
b) At infinity
c) At center of Earth
d) On Moon’s surface
Answer: c) At center of Earth
Explanation: Potential energy is most negative at the center.
86. The weight of an object is less on the Moon because:
a) Moon’s radius is smaller
b) Moon’s mass is smaller
c) Moon’s gravitational acceleration is smaller
d) All of the above
Answer: d) All of the above
Explanation: All contribute to lower gravity on the Moon.
87. The acceleration due to gravity on Mars is:
a) Less than Earth
b) Greater than Earth
c) Equal to Earth
d) Zero
Answer: a) Less than Earth
Explanation: Mars has lower mass and size than Earth.
88. What is the SI unit of gravitational potential?
a) Joule
b) Joule per kilogram (J/kg)
c) Newton
d) Newton-meter
Answer: b) Joule per kilogram (J/kg)
Explanation: Potential energy per unit mass.
89. The energy required to move a unit mass from Earth’s surface to infinity is called:
a) Kinetic energy
b) Escape energy
c) Gravitational potential energy
d) Mechanical energy
Answer: b) Escape energy
Explanation: Escape energy needed to break free from Earth’s gravity.
90. For a satellite in circular orbit, total energy is:
a) Positive
b) Negative
c) Zero
d) Infinite
Answer: b) Negative
Explanation: Total mechanical energy is negative in bound orbit.
91. Which of the following quantities is a scalar?
a) Gravitational force
b) Gravitational potential
c) Acceleration due to gravity
d) Velocity of satellite
Answer: b) Gravitational potential
Explanation: Potential is scalar; force and acceleration are vectors.
92. When a body moves from Earth’s surface to a height equal to Earth’s radius, the acceleration due to gravity becomes:
a) 
b)
c)
d)
Answer: a)
Explanation: 
.
93. A planet has twice the mass and radius of Earth. Its surface gravity is:
a) Twice Earth’s gravity
b) Same as Earth’s gravity
c) Half Earth’s gravity
d) Four times Earth’s gravity
Answer: c) Half Earth’s gravity
Explanation: 
.
94. The gravitational force between two point masses is 9 N. If one mass is doubled and distance halved, the force is:
a) 18 N
b) 36 N
c) 72 N
d) 9 N
Answer: c) 72 N
Explanation: New force 
.
95. The shape of the Earth’s orbit around the Sun is:
a) Perfect circle
b) Ellipse
c) Parabola
d) Hyperbola
Answer: b) Ellipse
Explanation: Kepler’s first law states orbits are elliptical.
96. The force of gravity between two masses is 10 N. If the distance between them is tripled, the force becomes:
a) 30 N
b) 3.33 N
c) 1.11 N
d) 0.11 N
Answer: c) 1.11 N
Explanation: 
, so 
.
97. The unit of universal gravitational constant G is:
a) 
b) 
c) 
d) 
Answer: a)
Explanation: From 
.
98. The orbital speed of a satellite depends on:
a) Its mass and orbital radius
b) Only orbital radius
c) Mass of planet and orbital radius
d) Mass of satellite only
Answer: c) Mass of planet and orbital radius
Explanation: 
.
99. The total mechanical energy of a satellite in orbit is:
a) Zero
b) Equal to kinetic energy
c) Equal to potential energy
d) Negative and equal to half of potential energy
Answer: d) Negative and equal to half of potential energy
Explanation: 
.
100. The force of gravity between two point masses separated by a distance r is:
a) Directly proportional to r
b) Inversely proportional to r
c) Directly proportional to
d) Inversely proportional to
Answer: d) Inversely proportional to
Explanation: Newton’s law of gravitation.