Question

At surface of earth weight of a person is $72N$ then his weight at height $R/2$ from surface of earth is $(R=\text{radius of earth})$

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

Answer 1

The correct option is D $32N$

Formula used: $W=mg$
Given,$W=72N$
$h=\frac{R}{2}$
Weight of the body at height $R$,
$W^{\prime }=W{\left(\frac{R}{R+h}\right)}^2$
$W{\left(\frac{R}{R+\frac{R}{2}}\right)}^2=W{\left(\frac{2}{3}\right)}^2$

$\frac{4}{9}W=\frac{4}{9}\times 72=32N$

Final Answer: (c)