posted by Troy on .
A soccer ball is kicked from the ground with an initial speed of 18.9 m/s at an upward angle of 47.0˚. A player 54.4 m away in the direction of the kick starts running to meet the ball at that instant. What must be his average speed if he is to meet the ball just before it hits the ground? Neglect air resistance.
Vo = 18.9m/s[47o]
Xo = 18.9*cos47 = 12.9 m/s.
Range = Vo^2*sin(2A)/g
Range = 18.9^2*sin94/9.8 = 36.4 m.
Range = Xo * t = 36.4 m.
12.9 * t = 36.4
t = 2.82 s. in flight.
d = 54.4-36.4 = 18 m To run in 2.82 s.
Speed = d/t = 18m/2.82s = 6.38 m/s.