Question

A particle of mass $m$ is projected with speed $u$ at angle $\theta$ with horizontal from ground. The work done by gravity on it during its upward motion is

• A. $\frac{-m u^{2} \sin ^{2} \theta}{2}$
• B. $\frac{m u^{2} \cos ^{2} \theta}{2}$
• C. $\frac{m u^{2} \sin ^{2} \theta}{2}$
• D. Zero

Answer 1

Answer: (A)

Height covered by projectile $=\frac{u^{2} \sin ^{2} \theta}{2 g}$
$W=-m g\left(\frac{u^{2} \sin ^{2} \theta}{2 g}\right)$
$=\frac{-m u^{2} \sin ^{2} \theta}{2}$