Question

to what height the body is to be raised so that force of gravity on it is 1% of the value on the surface of Earth? ( radius of earth is 6400 km)

Answer 1

Answer:

Correct option is

A

1600km

Let the force of gravitational on an object of mass m at an altitude h from earth's surface be equal to F.

Radius of earth =R

e

=6400km

and mass of earth be M

e

.

F=G

(R

e

+h)

2

M

e

m

=mg

′

So, g

′

=

(R

e

+h)

2

GM

e

g=

R

e

2

GM

e

g

g

′

=(

R

e

+h

R

e

)

2

=

100

64

R

e

+h

R

e

=0.8

So the altitude =h=

4

R

e

=1600km

Hence,

option (A) is correct answer.