Question:
A cricket bowler releases the ball in two different ways
(a) giving it only horizontal velocity and
(b) giving it horizontal velocity and a small downward velocity.
The speed vs at the time of release is the same. Both are released at a height H from the ground. Which one will have greater speed when the ball hits the
ground? Neglect air resistance.
Solution:
(a)
$\frac{1}{2} v_{z}^{2}=g H \Rightarrow v_{z}=\sqrt{2 g H}$
Speed at ground is given as:
$\sqrt{v_{s}^{2}+v_{z}^{2}}=\sqrt{v_{s}^{2}+2 g H}$
(b)
$\frac{1}{2} m v_{s}^{2}+m g H$ is the total energy of the ball when it hits the ground.
Therefore, (a) and (b) have the same speed.