NEET Physics Chapter Wise Mock Test – Gravitation
The magnitude of the force of gravity between two identical objects is given by F0. If the mass of each object is doubled but the distance between them is halved, then the new force of gravity between the object will be
The distance of the centres of moon and earth is D. The mass of the earth is 81 times the mass of the moon. At what distance from the centre of the earth, the gravitational force on a particle will be zero?
Two spheres of same size, one of mass 2 kg and another of mass 4 kg are dropped simultaneously from the top of Qutub Minar (height =72 m). When they are 1 m above the ground, the two spheres have the same
(b) kinetic energy
(c) potential energy
The weight of a body on the surface of the earth is 63 N. What is the gravitational force on it due to the earth at a height equal to half the radius of earth?
(a) 34 N
(b) 28 N
(c) 39 N
(d) 42 N
The speed of earth’s rotation about its axis is co. Its speed is increased to x times to make the effective acceleration due to gravity equal to zero at the equator. Then, x is
Imagine a new planet having the same density as that of earth but it is 3 times bigger than the earth in size. If the acceleration due to gravity on the surface of earth is g and that on the surface of the new planet is g’, then .
(a) g’ = 3g
(b) g’ = g/9
(c) g’ = 9g
(d) g’ = 27g
The density of newly discovered planet is twice that of earth. The acceleration due to gravity at the surface of the planet is equal to that at the surface of the earth. If the radius of the earth is R, the radius of the planet would be
If the distance between the earth and sun were half its present vdlue, the number of days in a year would have been
A geostationary satellite orbits around the earth in a circular orbit of radius 36000 km. Then, the time period of a spy-satellite orbiting a few 100 km above the earth’s surface (R = 6400 km) will approximately be
(b) 1 h
(c) 2 h
(d) 4 h
The ratio of mean distances of three planets from the sun are 0.5 :1:1.5, then the square of time periods are in the ratio of
(a) 1: 4 : 9
(d) 2 :1: 3
In a gravitational field, if a body is bound with the earth, then total mechanical energy has
(d) may be positive, negative or zero
When a body is lifted from surface of the earth to a height equal to the radius of the earth, then the change in its potential energy is
(b) 2 mgR
(c) 1/2 mgR
(d) 4 mgR
There is a crater of depth R/100 on the surface of the moon of radius R. A projectile is fired vertically upwards from the crater with a velocity equal to the escape velocity v from the surface of the moon. Maximum height attained by the projectile is
An object of mass m is raised from the surface of the earth to a height equal to the radius of the earth, that is, taken from a distance R to 2R from the centre of the earth. What is the gain in its potential energy?
(a) 1/2 mgR
(b) 1/4 mgR
(c) 1/2 mgR2
(d) 1/6 mgR
The velocity with which a projectile must be fired to escape from the earth does not depend upon
(a) mass of earth
(b) mass of projectile
(c) radius of earth
(d) None of these
Escape velocity on the earth is 11.2 kms-1. What would be the escape velocity on a planet whose mass is 1000 times and radius is 10 times that of earth?
(a) 112 kms-1
(b) 11.2 kms-1
(c) 1.12 kms-1
(d) 3.7 kms-1
An earth satellite is moved from one stable circular orbit to another higher stable circular orbit. Which one of the following quantities increase for the satellite as a result of this change?
(a) Angular momentum
(b) Kinetic energy
(c) Angular velocity
(d) Linear orbital speed
Two satellites of earth, S1 and S2 are moving in the same orbit. The mass of S1, is four times the mass of S2. Which one of the following statements is true?
(a) The time period of S1 is four times that of S1
(b) The potential energies of earth and satellite in the two cases are equal
(c) S1 and S2 are moving with the same speed
(d) The kinetic energies of the two satellites are equal
A particle is fired vertically upwards with a speed of 15 kms-1 from the surface of earth. The speed with which it moves in intersteller space, is
(take escape speed from surface of earth as 11.2 kms-1)
(b) 3.8 kms-1
(c) ≅ 10 kms-1
(d) ≅ 4kms-1
Network done on a satellite revolving in an elliptical orbit in one complete revolution
(a) is zero
(b) is non-zero
(c) may be zero
(d) None of these
Direction (Q. Nos. 40-45): In each of the following questions a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statements, mark the correct answer as
(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
(b) If both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion
(c) If Assertion is true but Reason is false
(d) If both Assertion and Reason are false
Assertion (A): Acceleration due to moon’s gravity on moon’s surface is ge/6 Acceleration due to earth’s
gravity on moon’s surface is ge/(60)2
Reason (R): The distance of moon from earth’s centre is approximately equal to 60 times the radius of earth.
Assertion (A): Due to binding energy of satellite, it is attached with the earth.
Reason (R): Binding energy of the particle is given by
BE = E = – GmM/R
Assertion (A): Areal velocity of a planet around sun will become two times, if mass of planet is halved.
Reason (R): Areal velocity = L/2m where L is angular momentum of planet about centre of sun.
Assertion (A): There is no effect of rotation of earth on acceleration due to gravity at poles.
Reason (R): Rotation of earth is about polar axis.
If the value of g at the surface of the earth is 9.8 m/s2, then the value of g at a place 480 km above the surface of the earth will be (radius of the earth is 6400 km)
(a) 8.4 m/s2
(b) 9.8 m/s2
(c) 7.2 m/s2
(d) 4.2 m/s2
If the earth stops moving around its polar axis, then what will be effect on body placed at South axis?
(a) Remain same
(c) Decrease but not zero
(d) Decrease and zero
The height at which the weight of a body becomes 1/16th, its weight on the surface of earth (radius R), is
Assuming the earth to be a sphere of uniform mass density, how much would body weight half way down to the centre of earth, if it weighed 250N on the surface?
(a) 150 N
(b) 175 N
(d) 200 N
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 3v, then the speed of satellite B will be
A particle of mass M is situated at the centre of a spherical shell of same mass and radius a. The gravitational potential at a point situated at a/2 distance from the centre, will be
Infinite number of bodies, each of mass 2 kg are situated on x-axis at distance 1 m, 2 m, 4 m, 8 m respectively from the origin. The resulting gravitational potential due to this system at the origin will be
A body of mass m taken from the earth’s surface to the height equal to twice the radius (R) of the earth. The change is potential energy of body will be
(a) mg 2R
(c) 3 mgR
A black hole is an object whose gravitational field is so strong that even light cannot escape from it. To what approximate radius would earth (mass =5.98×1024 kg) have to be compressed to a black hole?
(a) 10-9 m
(b) 10-6 m
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