83 free MCQs on Gravitation, each with its own worked answer and explanation. Universal gravitation, orbital mechanics, gravitational potential, and escape velocity.
Take the timed Gravitation chapterwise test →83 practice questions on Gravitation, sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Gravitation notes.
g is maximum at Earth's surface; going up, it falls off as 1/r² (inverse-square); going down, it falls off linearly with depth (since only the mass enclosed within radius r contributes), reaching zero at the centre.
Q1.
The acceleration due to gravity of a freely falling body does NOT depend on:
Q2.
Taking the reference at infinity, the gravitational potential energy of a two-body system is:
Q3.
The value of g on the Earth is greatest:
Q4.
The escape velocity from a planet depends on:
Q5.
Value of gravitational acceleration g at Earth's surface is approximately:
Q6.
As we go higher from Earth's surface, the value of g:
Q7.
Universal gravitational constant G has the value:
Q8.
Kepler's second law (equal areas in equal time) is a consequence of:
Q9.
Escape velocity from Earth's surface is approximately:
Q10.
The gravitational force between two masses is proportional to:
Q11.
Orbital velocity of a satellite near Earth's surface is approximately:
Q12.
Time period of a geostationary satellite is:
Q13.
An astronaut in an orbiting satellite experiences weightlessness because:
Q14.
Gravitational force is a _____ force:
Q15.
If distance between two masses doubles, gravitational force becomes:
Q16.
Kepler's third law states that T<sup>2</sup> is proportional to:
Q17.
Weight of a body on Moon is about _____ of weight on Earth:
Q18.
Gravitational PE of a mass m at height h above Earth's surface (for h << R) is:
Q19.
The orbits of all planets around Sun are:
Q20.
At the center of Earth, the value of g is:
Q21.
A planet closer to the Sun moves _____ compared to a distant planet:
Q22.
Which force keeps the Moon in orbit around Earth?
Q23.
Relation between escape velocity (ve) and orbital velocity (vo) at Earth's surface:
Q24.
Gravitational force obeys Newton's:
Q25.
The escape velocity from Earth is 11.2 km/s. If a body is projected at 22.4 km/s, its speed far away from Earth (ignoring other bodies) is about:
Q26.
A planet orbits the Sun at four times the Earth-Sun distance. Its orbital period (year) is about:
Q27.
A body weighs 100 N at the Earth surface. At a depth equal to one-fourth of the Earth radius, its weight is:
Q28.
The orbital period of a satellite skimming very close to a planet's surface depends only on the planet's:
Q29.
A satellite orbits at height equal to Earth's radius R (i.e., at distance 2R from center). Orbital velocity compared to surface orbital velocity:
Q30.
At what height h above Earth's surface is g reduced to one-fourth its surface value?
Q31.
Time period of satellite at height h from Earth's surface:
Q32.
Two bodies of mass M and m are at distance r. At what distance from M is the gravitational field zero?
Q33.
If Earth suddenly stopped rotating, weight of a person at equator would:
Q34.
Orbital velocity of satellite at height h from Earth (radius R, mass M):
Q35.
A satellite in low Earth orbit completes one revolution in about:
Q36.
Total mechanical energy of a satellite in circular orbit of radius r (mass m, Earth mass M):
Q37.
Gravitational potential V at distance r from mass M is:
Q38.
Energy required to send satellite from surface to orbit at radius r=2R (R=Earth's radius, M=Earth's mass):
Q39.
At poles, g is slightly greater than at equator because:
Q40.
Gravitational field intensity at surface of Earth (radius R, mass M) is:
Q41.
Ratio of orbital velocity to escape velocity at Earth's surface:
Q42.
If mass of Earth doubled but radius stayed same, escape velocity would:
Q43.
A planet has mass 2M and radius 2R. Surface gravity compared to Earth:
Q44.
Black holes have escape velocity equal to or greater than:
Q45.
Binding energy of a satellite in orbit at radius r is:
Q46.
For an orbit to be geosynchronous, it must be over:
Q47.
Value of g at depth d below Earth's surface:
Q48.
The gravitational PE of a body of mass m at distance r from Earth's center (M = Earth mass) is:
Q49.
The escape velocity from a planet is 11.2 km/s. If its radius is doubled while its mean density stays the same, the new escape velocity is:
Q50.
The gravitational potential energy of a 2 kg mass resting on a planet surface is −8 × 10<sup>7</sup> J. The escape speed from that surface is about:
Q51.
Two equal point masses M are separated by a distance 2a. The gravitational potential at the midpoint between them is:
Q52.
A planet has the same mean density as another but twice its radius. Its escape velocity, compared with the smaller planet, is:
Q53.
A body is dropped from rest at a height equal to the Earth radius R above the surface. Its speed on reaching the surface is about (g = 10 m/s<sup>2</sup>, R = 6.4×10<sup>6</sup> m):
Q54.
A geostationary satellite orbits at approximately what height above the Earth surface?
Q55.
At a distance r from the centre inside a uniform solid sphere of radius R (r < R), the gravitational field is proportional to:
Q56.
Planet A has twice the mass and four times the radius of planet B. Ratio of g<sub>A</sub> to g<sub>B</sub>:
Q57.
Two planets have time periods in ratio 8:1. Ratio of orbital radii:
Q58.
A satellite changes orbit from r<sub>1</sub> to r<sub>2</sub> (r<sub>2</sub> > r<sub>1</sub>). Change in KE is:
Q59.
Angular velocity of Moon around Earth: T = 27 days. Angular velocity in rad/s:
Q60.
A body is projected vertically upward from Earth's surface with speed ve/2 (ve = escape speed). Max height reached:
Q61.
Escape velocity on the Moon (g<sub>moon</sub> = g/6, R<sub>moon</sub> = R/4):
Q62.
A satellite is in circular orbit. When it loses energy due to air resistance, its orbital speed:
Q63.
A satellite at radius r from Earth center has angular momentum L. If radius decreases to r/4 (no external torque), new angular momentum is:
Q64.
A planet is at perihelion (closest) and aphelion (farthest). Speed ratio v<sub>perihelion</sub> : v<sub>aphelion</sub> equals:
Q65.
Gravitational potential at a point is -5 x 10<sup>7</sup> J/kg. Work done to bring 1 kg mass from infinity to this point is:
Q66.
Tidal forces on Earth due to Moon cause:
Q67.
If Earth's mass is M, radius R, orbital velocity at height h = R (i.e., r = 2R) in terms of g and R:
Q68.
Minimum energy needed to launch a satellite from Earth's surface to circular orbit at radius 2R:
Q69.
Gravitational field is zero at all interior points of a uniform hollow spherical shell. This is because:
Q70.
Two satellites orbit at 2R and 3R from Earth center. Period ratio T<sub>1</sub>:T<sub>2</sub>:
Q71.
A satellite in orbit has KE = K. Its total energy is:
Q72.
Gravitational force between two 1 kg masses 1 m apart is:
Q73.
A tunnel is drilled through Earth's center. A ball dropped into it undergoes:
Q74.
Binary stars of mass M each orbit their center of mass at distance d apart. Orbital period T in terms of G, M, d:
Q75.
Chandrasekhar limit refers to the maximum mass of:
Q76.
A planet has the same radius as Earth but twice its mass. If Earth escape velocity is 11.2 km/s, the escape velocity from this planet is:
Q77.
A satellite orbits at radius r with period T. If the orbital radius is increased to 4r, the new period is:
Q78.
The acceleration due to gravity at a depth equal to half the Earth radius (compared with the surface value g) is:
Q79.
At a height equal to the Earth radius above the surface, the acceleration due to gravity becomes:
Q80.
The total mechanical energy of a satellite of mass m in a circular orbit of radius r around a planet of mass M is:
Q81.
A planet moves in an elliptical orbit. If its aphelion distance is 4 times its perihelion distance, the ratio of its perihelion speed to aphelion speed is:
Q82.
A planet has twice the radius of Earth but the same mean density. The surface gravity on the planet, compared with Earth g, is:
Q83.
Two satellites move in the same circular orbit around Earth, one having twice the mass of the other. Their orbital speeds are:
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