Question

For a satellite escape velocity is $$11\,km/s.$$  If the satellite is launched at an angle of $${60^ \circ }$$ with the vertical, then escape velocity will be

A. $$11\,km/s$$  
B. $$11\sqrt 3 \,km/s$$
C. $$\frac{{11}}{{\sqrt 3 }}km/s$$
D. $$33\,km/s$$
Answer :   $$11\,km/s$$
Solution :
Escape velocity on earth (or any other planet) is defined as the minimum velocity with which the body has to be projected vertically upwards from the surface of the earth (or any other planet). So, that it just crosses the gravitational field of earth and never returns on its own. The escape velocity of the earth is given by
$${v_e} = \sqrt {\frac{{2GM}}{R}} = \sqrt {2gR} = \sqrt {\frac{{8\pi \rho G{R^2}}}{3}} $$
From above equation it is clear that value of escape velocity of a body does not depend upon the mass $$\left( m \right)$$ of the body and its angle of projection from the surface of the earth or the planet. So, escape velocity remains same.

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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