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Free download in PDF Class 11 Physics Chapter 8 Gravitation Multiple Choice Questions and Answers for Board, JEE, NEET, AIIMS, JIPMER, IIT-JEE, AIEE and other competitive exams. MCQ Questions for Class 11 Physics with Answers were prepared based on the latest exam pattern. These short solved questions or quizzes are provided by Gkseries. These will help the students for preparation of their examination./p>
(1)
Satellites orbiting 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.
Answer: of viscous forces causing the speed of satellite and hence height to gradually decrease.
(2)
Different points in earth are at slightly different distances from the sun and hence experience different forces due to gravitation. For a rigid body, we know that if various forces act at various points in it, the resultant motion is as if a net force acts on the c.m. (centre of mass) causing translation and a net torque at the c.m. causing rotation around an axis through the c.m. For the earth-sun system (approximating the earth as a uniform density sphere)
[A]
the torque is zero.
[B]
the torque causes the earth to spin.
[C]
the rigid body result is not applicable since the earth is not even approximately a rigid body.
[D]
the torque causes the earth to move around the sun.
Answer: the torque is zero.
(3)
As observed from earth, the sun appears to move in an approximate circular orbit. For the motion of another planet like mercury as observed from earth, this would
[A]
be similarly true.
[B]
not be true because the force between earth and mercury is not inverse square law.
[C]
not be true because the major gravitational force on mercury is due to sun.
[D]
not be true because mercury is influenced by forces other than gravitational forces.
Answer: not be true because the major gravitational force on mercury is due to sun.
(4)
A body of mass m rises to height h = R/5 from the earths surface , where R is earths radius . If g is acceleration due to gravity a earths surface , the increase in potential energy of the body is
[A]
mgh
[B]
(4/5) mgh
[C]
(5/6) mgh
[D]
(6/7) mgh
(5)
The masses of two planets are in the ratio 1 : 2. Their radii are in the ratio 1 : 2. The acceleration due to gravity on the planets are in the ratio.
[A]
1:2
[B]
2:1
[C]
3:5
[D]
5 : 3
(6)
Fg and Fe represents gravitational and electrostatic forces respectively, between the two electrons situated at a distance of 10 m. The ratio Fg/Fe is of the order of
[A]
1043
[B]
1036
[C]
1043
[D]
1036
(7)
A planet has twice the radius but the mean density is 1/4th as compared to earth. What is the radio of the escape velocity from the earth to that from the planet?
[A]
3:1
[B]
1:2
[C]
1:1
[D]
2:1
(8)
A satellite S is movin in an elliptical orbit around the earth . The mass of the satellite is very small compared to the mass of the earth .
[A]
The acceleration of S is always directed towards the centre of the earth .
[B]
The angular momentum of S about the centre of the earth changes in direction , but its magnitude remains constant .
[C]
The total mechanical energy of S varies periodically with time .
[D]
The linear momentum of S remains constant in magnitude .
Answer: The acceleration of S is always directed towards the centre of the earth .
(9)
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
(10)
If g is the acceleration due to gravity on the earths surface , the gain in the potential energy of an object of mass m raised from the surface of the earth to a height qeual to the radius R of the earth is
[A]
2 mgR
[B]
(1/2) mgR
[C]
(1/4) mgR
[D]
mgR
(11)
A satellite is revolving around the sun in a circular orbit with uniform velocity v. If the gravitational force suddenly disappears, the velocity of the satellite will be
[A]
zero
[B]
v
[C]
2v
[D]
infinity
(12)
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]
2 v
[C]
√ 2 v
[D]
√ 3 v
(13)
The ratio of the kinetic energy required to be given to the satellite to escape earths gravitational field to the kinetic energy required to be given so that the satellite moves in a circular orbit just above arths atmosphere is
[A]
one
[B]
two
[C]
half
[D]
infinite
(14)
If escape velocity from the earths surface is 11.2 km/sec. then escape velocity from a planet of mass same as that of earth but radius one fourth as that of earth is
[A]
11.2 km/sec
[B]
22.4 km/sec
[C]
5.65 km/sec
[D]
44.8 km/sec
(15)
The escape velocity from the earths surface is 11 km/sec. A certain planet has a radius twice that of the earth but its mean density is the same as that of the earth. The value of the escape velocity from this planet would be
[A]
22 km/sec
[B]
11 km/sec
[C]
5.5 km/sec
[D]
16.5 km/sec
(16)
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
(17)
A satellite is revolving around the earth in a circular orbit with a velocity of 7.07 km/s . What minimum increase in its velocity is needed to make it escape gravitational pull of earth ?
[A]
4.23 km/s in the direction of its velocity
[B]
11.3 km/s in a direction perpendicular to its velocity
[C]
2.93 km/s in the direction of its velocity
[D]
4.23 km/s in a direction perpendicular to its velocity
Answer: 2.93 km/s in the direction of its velocity
(18)
The change in the value of g at a height h above the surface of the earth is the same as at a depth d below the surface of earth . When both d and h are much smaller than the radius of the earth , then which one of the following is correct ?
[A]
d = 3h/2
[B]
d = h/2
[C]
d = h
[D]
d = 2h
(19)
The time -period of revolution of plante A around the sun is 8 times that of B . The distance of A from the sun is how many times greater than that of B from the sun ?
(20)
The mean radius of the earth is R, its angular speed on its own axis is w and the acceleration due to gravity at earths surface is g. The cube of the radius of the orbit of a geo-stationary satellite will be
[A]
r2g / w
[B]
R2w2 / g
[C]
RG w2
[D]
R2g / w2
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