Question

Q.38. A projectile of mass 2 kg is projected with speed 20 m/s at an angle $60°$ from horizontal. The work done by gravity on it during the time it reaches its highest point, is
(1) 173.2 J
(2) - 173.2 J
(3) 300 J
(4) - 300 J

Answer 1

$$\begin{gathered} maximumeightH=\frac{{20}^2{\sin }^{2}60}{2g}=\frac{3}{4}*20=15m \\ workdonebygravity=-mgH=-2*10*15=-300J \\ Regards \end{gathered}$$