Question

An athlete throws the ball up to a height of 6 what is the i risk velocity of the tennis ball.

Answer 1

According to the mechanical energy conservation, the kinetic energy at a time of launch is equal to the potential energy in the highest position:

$$\dfrac{mv_i^2}{2} = mgh$$

where $m$ is the mass of the ball, $v_i$ is the initial velocity, $h = 6m$ is the height and $g = 9.81m/s^2$ is the acceleration due to gravity. Expressing the intial velocity, obtain:

$$v_i = \sqrt{2gh} = \sqrt{2\cdot 9.81\cdot 6} \approx 10.85\space m/s$$

Answer. 10.85 m/s.