Question

The weight of a body on surface of earth is $12.6N$. When it is raised to a height half the radius of earth its weight will be

• A. 2.8 N
• B. 5.6 N
• C. 12.5 N
• D. 25.2 N

Answer 1

Answer: (B)

Weight of body on the surface of earth
$mg=12.6N$
At height $h$, the value of $g^{\prime }$ is given by
$g^{\prime }=g\frac{R^2}{(R+h{)}^2}.$
Now, $h=R/2$
$\therefore g^{\prime }=g{\left(\frac{R}{R+(R/2)}\right)}^2=g\frac{4}{9}$
Weight at height $h=mg\frac{4}{9}=12.6\times \frac{4}{9}=5.6N$