Question

A body weighs 72 N on the surface of the earth. What is the gravitational force on it due to the earth at a height equal to half the radius of the earth?

• A. 16 N
• B. 28 N
• C. 32 N
• D. 72 N

Answer 1

Answer: (C)

32 N

Answer 2

Weight of body on the surface of the earth = mg = 72 N

Accelerations due to gravity at height h is

Gravitational force on body at height h is

$\mathrm { F } = \mathrm { mg } _ { \mathrm { h } } = \mathrm { m } \times \frac { 4 } { 9 } \mathrm {~g} = \frac { 4 } { 9 } \times \mathrm { mg } = \frac { 4 } { 9 } \times 72 = 32 \mathrm {~N}$