Question

The height of the point vertically above the earth's surface, at which acceleration due to gravity becomes $$1\% $$ of its value at the earth's surface is (Radius of the earth = $$R$$ )

A. $$8\,R$$
B. $$9\,R$$  
C. $$10\,R$$
D. $$20\,R$$
Answer :   $$9\,R$$
Solution :
$$\eqalign{ & \frac{{g'}}{g} = {\left( {\frac{R}{{R + h}}} \right)^2} \Rightarrow \frac{1}{{100}} = {\left( {\frac{R}{{R + h}}} \right)^2} \cr & \Rightarrow h = 9R \cr} $$

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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