A football kicker lines up to kick a game winning kick. The goalpost is 30m away and the ball must clear the 3.3m high cross-bar. If the kick leaves his foot at an angle of 35 degrees, how fast must the kick be to be good?

Answer 1

Horizontal: d=Vh*time, or a) timeinair=30/(V*cos35)
vertical: Hf=hi+vi*t- gt^2/2 or b) 3.3=0+V*sin35:*t-4.9 t^2

Now put in these two equations for t, put time in air , and then solve for V

Answer 2

d = Vo^2*sin(2A)/g = 30.
Vo^2*sin70/9.8 = 30,
Vo^2 * 0.0959 = 30,
Vo = 17.7 m/s.