Question

A body is dropped from a certain height above the surface of the earth. When it loses $U$ amount of its potential energy, it acquires a velocity $v$ . The mass of the body is

• A. $\frac{2 U}{v^{2}}$
• B. $\frac{2 v}{U^{2}}$
• C. $\frac{2 v}{U}$
• D. $\frac{U^{2}}{2 v}$

Answer 1

Answer: (A)

Using the conservation of mechanical energy
$K_{i}+P_{i}=K_{f}+P_{f}$
$0+P=\frac{1}{2}mv^{2}+\left(P - U\right)$
$\frac{1}{2}mv^{2}=U$
$m=\frac{2 U}{v^{2}}$