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At surface of earth potential energy of a particle is U and potential is V. Change in potential energy and potential at height h=R are suppose U and V. Then.

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Important Questions on Gravitation

HARD
A mass 'm' on the surface of the Earth is shifted to a target equal to the radius of the Earth. If 'R' is the radius and 'M' is the mass of the Earth, then work done in this process is:
MEDIUM
The change in potential energy when a body of mass m is raised to a height nR from the earth's surface is (R=radius of earth),
EASY
A particle falls towards earth from infinity. Its velocity on reaching the earth would be:
MEDIUM
A rocket is launched vertically from the surface of the earth with an initial velocity equal to one-third of the escape velocity. If we ignore the atmospheric resistance, what will be the maximum height attained by the rocket?
MEDIUM
A rocket has to be launched from earth in such a way that it never returns. If E is the minimum energy delivered by the rocket launcher, what should be the minimum energy that the launcher should have, if the same rocket is to be launched from the surface of the moon? Assume that the density of the earth and the moon are equal and that the earth's volume is 64 times the volume of the moon.
EASY

If one wants to remove all the mass of the earth to infinity in order to break it up completely. The amount of energy that needs to be supplied will be x5GM2R, where x is ________.

(Round off to the Nearest Integer)

(M is the mass of earth, R is the radius of earth, G is the gravitational constant)

EASY

A spherically symmetric gravitational system of particles has mass density ρ=ρ0 for rR0 for r>R where, ρ0 is a constant. A test mass can undergo circular motion under the influence of the gravitational field of particles. Its speed v as a function of distance r(0<r<) from the centre of the system is represented by

EASY
Consider a satellite which is rotating in a circular orbit of radius 2RE about the earth. The mass of satellite is 1600 kg. What is the energy required to transfer it to a circular orbit of radius 8RE?
[use g=10 ms s-2, RE=6×106 m
MEDIUM
A uniform cable of mass M and length L is placed on a horizontal surface such that its 1nth part is hanging below the edge of the surface. To lift the hanging part of the cable upto the surface, the work done should be:
MEDIUM
What is the minimum energy required to launch a satellite of mass m from the surface of the earth of mass M and radius R at an altitude 2R?
MEDIUM
A particle of mass m is projected with a velocity v=kVe (k<1) from the surface of the earth (Ve= escape velocity). The maximum height above the surface reached by the particle is___
MEDIUM
Two bodies, each of mass M, are kept fixed with a separation of 2L. A particle of mass m is projected from the midpoint of the line joining their centers, perpendicular to the line. The gravitational constant is G. The correct statement (s) is (are) :
MEDIUM

A body of mass 2M splits into four masses {m,m,M-m,M-m}, which are rearranged to form a square as shown in the figure. The ratio of Mm for which, the gravitational potential energy of the system becomes maximum is x : 1. The value of x is ________.

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MEDIUM
The initial velocity vi required to project a body vertically upward from the surface of the earth to reach a height of 10R, where R is the radius of the earth, may be described in terms of escape velocity ve such that vi=xy×ve. The value of x will be
EASY
The gravity potential energy is maximum at
MEDIUM

Four spheres each of mass m form a square of side d (as shown in figure). A fifth sphere of mass M is situated at the centre of square. The total gravitational potential energy of the system is

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MEDIUM
The gravitational potential energy difference per unit mass between the surface of a planet and a point 100 m above it is 1000 Jkg-1. How much work is required to be done in moving an 5 kg object 100 m on a slope 30°to the horizontal on this planet?
HARD
A satellite of massM  is launched vertically upwards with an initial speed u from the surface of the earth. After it reaches height R ( R= radius of the earth), it ejects a rocket of mass M10 so that subsequently the satellite moves in a circular orbit. The kinetic energy of the rocket is ( G is the gravitational constant; Me is the mass of the earth):
MEDIUM
An object is propelled vertically to a maximum height of, 4R from the surface of a planet of radius, R and mass M. The speed of object when it returns to the surface of the planet is
MEDIUM
A planet is orbiting the sun in an elliptical orbit. Let U denote the potential energy and K denote the kinetic energy of the planet at an arbitrary point on the orbit. Choose the correct statement-