Question

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

• A. 48 N
• B. 32 N
• C. 30 N
• D. 24 N

Answer 1

Answer: (B)

32 N

Answer 2

$w_{s}=mg_{s}=72\,N$
$w_{h}=mg_{h}=\frac{mg_{s}}{\left(1+\frac{h}{R}\right)^{2}}$
$=\frac{72\,N}{\left(1+\frac{\frac{R }{2}}{2}\right)}$

$=\frac{72}{\frac{9 }{4}}$
$w_{h}=32\,N$