Question

A ball is thrown at an angle O with the horizontal.
Its kinetic energy is 100 J and it becomes
30 J at the highest point. The angle of projection
is-​

Answer 1

Explanation:

Initial kinetic energy =100 =

$\frac{1}{2} m{v}^{2} = 100$

At the highest point vertical component of velocity becomes 0.

Therefore only horizontal component of the velocity exists.

K.E at the highest point =

$\frac{1}{2} m( {v}^{2} { \cos( \alpha ) }^{2} ) \: = 30$

Therefore,