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A body weighs 72 N on the surface of the earth. What is the gravitational force on it due to earth at a height equal to half the radius of the earth from the surface?
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- 32 N
- 28 N
- 16 N
- 72 N
Correct Option: A
mg = 72 N (body weight on the surface)
| g = | ||
| R2 |
| At a height H = | ||
| 2 |
| g' = | - | ||||||
 | R + |  | 2 | 9R2 | |||
| 2 | |||||||
| Body weight at height H = | ||
| 2 |
| mg' = m × | ||||
| 9 | R2 |
| = m × | × g = | mg | ||
| 9 | 9 |
| = | × 72 = 32 N | |
| 9 |
