Q.1
A planet is revolving around the sun in an elliptical orbit, its closest distance from the sun is r and the farthest distance is R. If the orbital velocity of the planet closest to the sun be v, then what is the velocity at the farthest point.
  • a) vr/R
  • b) vR/r
  • c) v(r/R)1/2
  • d) v(r/R)1/2
Q.2
A uniform spherical shell gradually shrinks maintaining its shape. the gravitational potential at the centre
  • a) increases
  • b) decreases
  • c) remains constant
  • d) oscillates
Q.3
P is a point at distance r from centre of solid sphere of radius a. The gravitational potential at P is V. If V is plotted as a function of r, which is the correct curve?
  • a)
    ch-7_qn-151choice_img_no1.png
  • b)
    ch-7_qn-151choice_img_no2.png
  • c)
    ch-7_qn-151choice_img_no3.png
  • d)
    ch-7_qn-151choice_img_no4.png
Q.4
The eccentricity of the earth's orbit is 0.The ratio of its maximum speed in its orbit to its minimum speed is
  • a) 1.67
  • b) 1.034
  • c) 1
  • d) 0.167
Q.5
A body of mass 'm' taken from the earth's surface tothe height equal to twice the radius (R) of the earth.The change in potential energy of body will be…[NEET 2013]
  • a) mg2R
  • b) 2mgR/3
  • c) 3mgR
  • d) mgR/3
Q.6
Infinite number of bodies, each of mass 2 kg aresituated on x-axis at distance 1 m, 2 m, 4 m, 8 m, .....respectively, from the origin. The resultinggravitational potential due to this system at theorigin will be
  • a) - G
  • b) -8G/3
  • c) -4G/3
  • d) -4G
Q.7
A black hole is an object whose gravitationalfield is so strong that even light cannot escapefromit.To what approximateradiuswouldearth(mass = 5.98 × 1024 kg) have to becompressed to be a black hole?
  • a) 10–2 m
  • b) 100m
  • c) 10–9 m
  • d) 10–6 m
Q.8
Kepler’s third law states that square of period of revolution (T) of a planet around the sun, isproportional to third power of average distance r between sun and planeti.e. T2 = Kr3 here K is constant.If the masses of sun and planet are M and m respectively then as per Newton’s law of gravitation forceof attraction between them is=G Mm/r2 , here G is gravitational constant. The relation between G and K is described as :
  • a) K=1/G
  • b) GK = 4π2
  • c) GMK = 4π2
  • d) K = G
Q.9
A satellite S is moving in an elliptical orbit aroundthe earth. The mass of thesatellite is very smallcompared to the mass of the earth. Then,.. [RE AIPMT 2015]
  • a) the acceleration of S is always directed towardsthe centre of the earth.
  • b) the angular momentum of S about the centreof the earth changes in direction, but itsmagnitude remains constant.
  • c) the total mechanical energy of S variesperiodically with time.
  • d) the linear momentum of S remains constant inmagnitude.
Q.10
A remote - sensing satellite of earth revolves in acircular orbit at a height of 0.25 × 106 m above thesurface of earth. If earth's radius is 6.38 × 106 m and g=9.8 ms-2, then the orbital speed of thesatellite is :
  • a) 6.67 km s-1
  • b) 7.76 km s-1
  • c) 8.56 km s-1
  • d) 9.13 km s-1
Q.11
At what height from the surface of earth thegravitation potential and the value of g are –5.4 × 107 J kg–2 and 6.0 ms–2 respectively ?Take the radius of earth as 6400 km : …[ AIPMT 2016]
  • a) 2600 km
  • b) 1600 km
  • c) 1400 km
  • d) 2000 km
Q.12
The ratio of escape velocity at earth (ve) to the escape velocity at a planet (vp)whose radius and mean density are twice as that of earth is :-
  • a) 1 : 2
  • b) 1 : 2√2
  • c) 1 : 4
  • d) 1 : √2
Q.13
Starting from the centre of the earth having radius R, the variation of g ( acceleration due to gravity) is shown by …[ NEET II – 2016]
  • a)
    ch-7_qn-162choice_img_no1.png
  • b)
    ch-7_qn-162choice_img_no2.png
  • c)
    ch-7_qn-162choice_img_no3.png
  • d)
    ch-7_qn-162choice_img_no4.png
Q.14
A satellite of mass m is orbiting the earth(of radius R) at a height h from its surface. The totalenergy of the satellite in terms of g0, the value ofacceleration due to gravity at the earth's surface, is …[ NEET II – 2016]
  • a)
    ch-7_qn-163choice_img_no1.png
  • b)
    ch-7_qn-163choice_img_no2.png
  • c)
    ch-7_qn-163choice_img_no3.png
  • d)
    ch-7_qn-163choice_img_no4.png
Q.15
The acceleration due to gravity at a height 1 kmabove the earth is the same as at a depth d belowthe surface of earth. Then …[NEET 2016]
  • a) ½ m
  • b) 1 km
  • c) 3/2 km
  • d) 2 km
Q.16
Which of the following statements are correct? …[NEET 2017] (i) Centre of mass of a body always coincides withthe centre of gravity of the body. (ii) Centre of mass of a body is the point at whichthe total gravitational torque on the body is zero (iii) A couple on a body produce both translationaland rotational motion in a body. (iv) Mechanical advantage greater than one meansthat small effort can be used to lift a large load.
  • a) (ii) and (iv)
  • b) (i) and (ii)
  • c) (ii) and (iii)
  • d) (iii) and (iv)
Q.17
Two astronauts are floating in gravitational free spaceafter having lost contact with their spaceship. Thetwo will … [ NEET 2017]
  • a) Keep floating at the same distance between them
  • b) Move towards each other
  • c) Move away from each other
  • d) Will become stationary
Q.18
Consider a drop of rain water having mass 1 g fallingfrom a height of 1 km. It its the ground with a speedof 50 m/s. Take g constant with a value10 m/sThe work done by the (i) gravitational force and the (ii) resistive force of air is
  • a) (i) – 10 J (ii) –8.25 J
  • b) (i) 1.25 J (ii) –8.25 J
  • c) (i) 100 J (ii) 8.75 J
  • d) (i) 10 J (ii) –8.75 J
Q.19
What is the minimum energy required to launch a satellite of mass m from the surface of a planetof mass M and radius R in a circular orbit at an altitude of 2R ?
  • a)
    ch-7_qn-168choice_img_no1.png
  • b)
    ch-7_qn-168choice_img_no2.png
  • c)
    ch-7_qn-168choice_img_no3.png
  • d)
    ch-7_qn-168choice_img_no4.png
Q.20
then one correct answer Q169) Two bodies, each of mass M, are kept fixed with a separation 2L. A particle of mass m isprojected from the midpoint of the line joining their centres, perpendicular to the line. Thegravitational constant is G. The correct statement(s) is (are) … [ IIT Advance 2013]
  • a) The minimum initial velocity of the mass m to escape the gravitational field of the two bodies is
    ch-7_qn-169choice_img_no1.png
  • b) The minimum initial velocity of the mass m to escape the gravitational field of the two bodies is
    ch-7_qn-169choice_img_no2.png
  • c) The minimum initial velocity of the mass m to escape the gravitational field of the twobodies is
    ch-7_qn-169choice_img_no3.png
  • d) The energy of the mass m remains constant
Q.21
A planet of radius R =X/10 , (X radius of Earth) has the same mass density as Earth. Scientists dig a well of depth R/5 on it and lower a wire of the same length and of linearmass density 10−3 kgm−1 into it. If the wire is not touching anywhere, the force applied atthe top of the wire by a person holding it in place is (take the radius of Earth = 6 × 106 m and the acceleration due to gravity on Earth is 10 ms−2) [IIT Advance 2014]
  • a) 96 N
  • b) 108 N
  • c) 120 N
  • d) 150 N
Q.22
A rocket is launched normal to the surface of the Earth, away from the Sun, along the line joining the sun and the Earth. The Sun is 3 × 105 times heavier than the Earth and is at a distance 2.5 ×104 times larger than the radius of the Earth. The escape velocity from Earth's gravitational field is ve = 11.2 km s–The minimum initial velocity (vs) required for the rocket to be able to leave the Sun- Earth system is closest to (Ignore the rotation and revolution of the Earth and the presence of any other planet) [IIT Advance 2017]
  • a) vs = 22 km s–1
  • b) vs = 72 km s–1
  • c) vs = 42 km s–1
  • d) vs = 62 km s–1
Q.23
The radii of circular orbits of two satellites A and B of the earth, are 4R and R, respectively. If the speed of satellite A is 3 V, then the speed of satellite B will be: [ CBSE-PMT 2010]
  • a) 3V/4
  • b) 6V
  • c)12V
  • d)3V/2
Q.24
The earth ( mass=6 × 1024kg) revolves around the sun with an angular velocity 2 × 10-7 rad/sec in a circular orbit of radius=1.5 × 108km. The force exerted by sun on earth in newton is ...[ AFMC 1997, 1999]
  • a)36 × 1021
  • b) 18 × 1025
  • c)29 × 1039
  • d)zero
Q.25
The distance of two planets from the sun are 1013 and 1012 meters respectively. The ratio of time periods of these two planets is [ CBSE PMT 1988]
  • a) 1/√10
  • b) 100
  • c) 10√10
  • d) √10
Q.26
The largest and the shortest distance of the earth from the sun are r1and rIts distance from the sun when it is at perpendicular to the major-axis of the orbit drawn from the sun is [1988]
  • a) (r1 + r2)/4
  • b) (r1 + r2)/ (r1 - r2)
  • c) 2(r1 × r2)/ (r1 + r2)
  • d) (r1 + r2)/ 3
Q.27
If the gravitational force between two objects were proportional to 1/R (and not as 1/R2) where R is separation between them, then a particle in circular orbit under such a force would have its orbital speed v proportional to [1989]
  • a) 1/R2
  • b) R0
  • c) R
  • d) 1/R
Q.28
A planet is moving in an elliptical orbit around the sun. If T, V, E, and L stands for kinetic energy, gravitational potential, total energy, and magnitude of angular moment bout the center of force respectively
  • a) T is conserved
  • b) V is always positive
  • c) E is always negative
  • d) L is conserved but direction of vector L changes continuously
Q.29
For a satellite escape velocity is 11 km/s. If the satellite is launched at an angle of 60° with the vertical, then escape velocity will be [1989]
  • a) 11 km/s
  • b) 11 √3 km/s
  • c) 11 /√3 km/s
  • d) 33 km/s
Q.30
A satellite of mass am is orbiting around the earth in a circular orbit with a velocity v. What will be its total energy? [1991]
  • a) (3/4) mv2
  • b) (1/2) mv2
  • c) mv2
  • d)-(1/2)mv2
0 h : 0 m : 1 s