Question

A cricket ball hits at ${30}^0$ with the horizontal with kinetic energy $K$. The kinetic energy at the highest point is

• A. $zero$
• B. $\frac{K}{4}$
• C. $\frac{K}{2}$
• D. $\frac{3K}{4}$

Answer 1

Answer: (D)

$\frac{3K}{4}$

Speed at the highest point $v=u\cos {30}^{\circ }=\left(\frac{u\sqrt{3}}{2}\right)$
K.E at highest point $K^{\prime }=\frac{1}{2}m{v}^2$
$K^{\prime }=\frac{1}{2}m{u}^2\left(\frac{3}{4}\right)$
$K^{\prime }=\left(\frac{3K}{4}\right),K=\left(\frac{1}{2}m{u}^2\right).$