JEE Physics Gravitation MCQs Set A

Question. According to Kepler, planets move in
(a) Elliptical orbits around the sun with sun at one of its foci
(b) Straight lines with constant velocity
(c) Elliptical orbits around the sun with sun at exact centre
(d) Circular orbits around the sun

Answer: A

Question. In a satellite if the time of revolution is T, then PE is proportional to
(a) T^–2/3
(b) T^–4/3
(c) T³
(d) T^1/3

Answer: A

Question. The torque on a planet about the centre of sun is
(a) Zero
(b) Positive
(c) Negative
(d) Depend on mass of planet

Answer: A

Question. During motion of a planet from perihelion to aphelion the work done by gravitational force of sun on it is
(a) Negative
(b) May be positive or negative
(c) Zero
(d) Positive

Answer: A

Question. The gravitational constant depends upon
(a) None of these
(b) Gravitational mass
(c) Size of the bodies
(d) Distance between the bodies

Answer: A

Question. Gravitation is the phenomenon of interaction between
(a) Any arbitrary shaped masses
(b) Point masses only
(c) Planets only
(d) None of these

Answer: A

Question. Force of gravitation between two masses is found to be F, in vacuum. If both the masses are dipped in water at same distance then, new force will be
(a) F
(b) Cannot say
(c) < F
(d) > F

Answer: A

Question.  Two planets have same density but different radii. The acceleration due to gravity would be
(a) Greater on the larger planet
(b) Same on both planets
(c) Greater on the smaller planet
(d) Dependent on the distance of planet from the sun

Answer: A

Question. If the radius of earth shrinks by 1.5% (mass remaining same), then the value of gravitational acceleration changes by
(a) 3%
(b) –3%
(c) –2%
(d) 2%

Answer: A

Question. At what height above the surface of earth the value of "g" decreases by 2%? [radius of the earth is 6400 km]
(a) 64 km
(b) 128 km
(c) 1600 km
(d) 32 km

Answer: A

Question. During motion of a man from equator to pole of earth, its weight will (neglect the effect of change in the radius of earth)
(a) Increase by 0.34%
(b) Increase by 0.52%
(c) Decrease by 0.34%
(d) Decrease by 0.52%

Answer: A

Question. The value of g at the surface of earth is 9.8 m/s². Then the value of ‘g’ at a place 480 km above the surface of the earth will be nearly (radius of the earth is 6400 km)
(a) 8.5 m/s²
(b) 4.2 m/s²
(c) 7.2 m/s²
(d) 9.8 m/s²

Answer: B

Question. The value of g at the surface of earth is 9.8 m/s². Then the value of ‘g’ at a place 480 km above the surface of the earth will be nearly (radius of the earth is 6400 km)
(a) 8.5 m/s²
(b) 4.2 m/s²
(c) 7.2 m/s²
(d) 9.8 m/s²

Answer: A

Question. As we go from the equator to the poles, value of ‘g’
(a) Increases
(b) Decreases
(c) Remains the same
(d) First increase and then decrease

Answer: A

Question. The acceleration due to gravity on a planet is 1.96 m/s². If it is safe to jump from a height of 3 m on the earth, the corresponding height on the planet will be
(a) 15 m
(b) 9 m
(c) 6 m
(d) 3 m

Answer: A

Question. The escape velocity of a body from earth is about 11.2 km/s. Assuming the mass and radius of the earth to be about 81 and 4 times the mass and radius of the moon, the escape velocity in km/s from the surface of the moon will be
(a) 2.48
(b) 11
(c) 49.5
(d) 0.54

Answer: A

Question. A small satellite is revolving near earth’s surface. Its orbital velocity will be nearly
(a) 8 km/s
(b) 11.2 km/s
(c) 4 km/s
(d) 6 km/s

Answer: A

Question. When speed of a satellite is increased by x percentage, it will escape from its orbit, where the value of x is
(a) 41.4%
(b) 27.5%
(c) 34.4%
(d) 11.2%

Answer: A

Question. If potential energy of a satellite is –2MJ, then the binding energy of satellite is
(a) 1 MJ
(b) 2 MJ
(c) 8 MJ
(d) 4 MJ

Answer: A

Question. The time period of polar satellites is about
(a) 100 min
(b) 84.6 min
(c) 6 hr
(d) 24 hr

Answer: A

Question. If a satellite of mass 400 kg revolves around the earth in an orbit with speed 200 m/s then its potential energy is
(a) –16 MJ
(b) –2.4 MJ
(c) –8.0 MJ
(d) –1.2 MJ

Answer: A

Question. A satellite of the earth is revolving in a circular orbit with a uniform speed v. If the gravitational force suddenly disappears, the satellite will
(a) Move with a velocity v, tangentially to the original orbit
(b) Continue to move with velocity v along the original orbit
(c) Fall down with increasing velocity
(d) Ultimately come to rest somewhere on the original orbit

Answer: A

Question. The relay satellite transmits the television signals continuously from one part of the world to another because its
(a) Period is equal to the period of rotation of the earth about its axis
(b) Period has no relation with the period of the earth about its axis
(c) Period is less than the period of rotation of the earth
(d) Period is greater than the period of rotation of the earth

Answer: A

Question. If height of a satellite from the surface of earth is increased, then its
(a) All of these
(b) Kinetic energy will decrease
(c) Potential energy will increase
(d) Total energy will increase

Answer: A

Question. The gravitational force on a body of mass 1.5 kg situated at a point is 45 N. The gravitational field intensity at that point is
(a) 30 N/kg
(b) 67.5 N/kg
(c) 46.5 N/kg
(d) 43.5 N/kg

Answer: A

Question. An earth satellite X is revolving around earth in an orbit whose radius is one-fourth of the radius of orbit of a communication satellite. Time period of revolution of X is
(a) 3 hrs
(b) 6 hrs
(c) 4 days
(d) 72 days

Answer: A

Question. When a satellite moves around the earth in a certain orbit, the quantity which remains constant is
(a) Areal velocity
(b) Potential energy
(c) Kinetic energy
(d) Angular velocity

Answer: A

Question. A body weighs 72 N on surface of the earth. When it is taken to a height of h = 2R, where R is radius of earth, it would weigh
(a) 8 N
(b) 9 N
(c) 18 N
(d) 36 N

Answer: A

Question. If all objects on the equator of earth feel weightless then the duration of the day will nearly become
(a) 1.41 hr
(b) 2.2 hr
(c) 4.4 hr
(d) 6.2 hr

Answer: A

Question. If the gravitational potential energy of two point masses infinitely away is taken to be zero then gravitational potential energy of a galaxy is
(a) Negative
(b) Positive
(c) Zero
(d) Can have any value

Answer: A