At what distance above and below the surface of the earth a body will have same weight. (take radius of earth as R.)
- 3R-R2
- R2
- 5R-R2
- 5R-R
Answer
(3) 5R-R2
Solution
Height h: gh= g (1+ hR )2; depth h: gd=g (1- hR )
same weight gh=gd. Put x= hR:
(1-x)(1+x)2=1
x-x2-x3=0 x2+x-1=0
x= 5-12 h= 5R-R2
Answer: (3)