question_answer

A body has a weight 72 N. When it is taken to a height \[h=R\] (radius of earth), it would weigh:        [AIPMT 2000]

A) 72 N    

B) 36 N   

C) 18 N

D) zero

Correct Answer: C

Solution :

Key Idea: At a height h from earth’s surface, the value of acceleration due to gravity is

The acceleration due to gravity at height h from earth’s surface is

Weight of a body at height h

Now at height h equal to radius (R) of earth i.e.,  we have

or

but         (given)