Question

A particle is suspended from a spring and it stretches the spring by $$1\,cm$$  on the surface of earth. By how much amount the same particle will stretch the same spring at a place $$800\,km$$  above the surface of earth.

A. $$1.59\,cm$$
B. $$2.38\,cm$$
C. $$0.79\,cm$$  
D. $$1.38\,cm$$
Answer :   $$0.79\,cm$$
Solution :
$$\eqalign{ & x = \frac{{mg}}{k} = \frac{{GMm}}{{{R^2}}}k \Rightarrow x \propto \frac{1}{{{R^2}}} \Rightarrow {x_2} \cr & = {\left( {\frac{{6400}}{{790n}}} \right)^2}{x_1} = 0.79\,cm \cr} $$

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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