A regulation volleyball court is L = 18.0 m long and a regulation volleyball net is d = 2.43 m high. A volleyball player strikes the ball a height h = 1.74 m directly above the back line, and the ball's initial velocity makes an angle theta = 31o with respect to the ground.At what initial speed must the ball be hit so that it lands directly on the opponent's back line?

1 answer

horizontal distance=18m
hf=hi+vi*time-1/2 g t^2
a) 0=1.74+v*sin31*t-4.8 t^2
b) and 18m=vcos31*t or t=18/(vcos31)
put that value of t into a), solve for v. A little algebra will be required. It is likly to be a quadratic equation.