Question

The gravitational field due to a mass distribution is $$E = \frac{K}{{{x^3}}}$$   in the $$x$$-direction. ($$K$$ is a constant). Taking the gravitational potential to be zero at infinity, its value at a distance $$x$$ is

A. $$\frac{K}{x}$$
B. $$\frac{K}{{2x}}$$
C. $$\frac{K}{{{x^2}}}$$
D. $$\frac{K}{{2{x^2}}}$$  
Answer :   $$\frac{K}{{2{x^2}}}$$
Solution :
$$V = - \int_\infty ^x E dx = \int_\infty ^x K {x^{ - 3}}dx = \frac{K}{{2{x^2}}}.$$

Releted MCQ Question on
Basic Physics >> Gravitation

Releted Question 1

If the radius of the earth were to shrink by one percent, its mass remaining the same, the acceleration due to gravity on the earth’s surface would-

A. Decrease
B. Remain unchanged
C. Increase
D. Be zero
Releted Question 2

If $$g$$ is the acceleration due to gravity on the earth’s surface, the gain in the potential energy of an object of mass $$m$$ raised from the surface of the earth to a height equal to the radius $$R$$ of the earth, is-

A. $$\frac{1}{2}\,mgR$$
B. $$2\,mgR$$
C. $$mgR$$
D. $$\frac{1}{4}mgR$$
Releted Question 3

If the distance between the earth and the sun were half its present value, the number of days in a year would have been-

A. $$64.5$$
B. $$129$$
C. $$182.5$$
D. $$730$$
Releted Question 4

A geo-stationary satellite orbits around the earth in a circular orbit of radius $$36,000 \,km.$$   Then, the time period of a spy satellite orbiting a few hundred km above the earth's surface $$\left( {{R_{earth}} = 6400\,km} \right)$$    will approximately be-

A. $$\frac{1}{2}\,hr$$
B. $$1 \,hr$$
C. $$2 \,hr$$
D. $$4 \,hr$$

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Gravitation


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