Q 11-05-015NEETEAMCET 2014 (Medical)Easy
A body of $200$ g begins to fall from a height where its potential energy is $80$ J. Its velocity (in m/s) at a point where its kinetic and potential energies are equal is
Answer: (D) $20$
Total mechanical energy $= 80$ J. Where KE = PE, each is $40$ J:
$$\frac{1}{2}(0.2)v^2 = 40 \;\Rightarrow\; v^2 = 400 \;\Rightarrow\; v = 20\ \text{m/s}$$
Solution by Sreeraj P, M.Sc Physics