finding initial vertical velocity and final vertical velocity - projectile motion

Question

find initial vertical velocity and final vertical velocity when a ball has a mass of 280g, flight time of 0.69s and has a length of 0.76m. height of strike is 0.8m.

this is a projectile motion question. i'm a little bit stuck since it doesn't give angle - thanks

Answer 1

HINT

From the following

• $ x = v_0 t \cos(\theta)$
• $y = v_0 t \sin(\theta) - \frac{1}{2}gt^2$

set

• $y_{max} = v_0 (\bar t/2) \sin(\theta) - \frac{1}{2}g(\bar t/2)^2$
• $ x_{max} = v_0 \bar t \cos(\theta)$

from which find $\theta$ and $v_0$.