Question

A soccer ball is kicked with the initial speed of 10.7m/s . After 0.780s it is at its highest point. What was its initial direction of motion?

Answer 1

v = Vi - g t
v = 0 at top
0 = Vi - 9.81(.78)
Vi = 7.65 m/s initial speed up

sin T = 7.65/10.7
T = 45.65 degrees up from horizontal

Answer 2

Vy = vo sinθ - gt
0 = 10.7 sinθ - (9.81 x 0.780)

sinθ = gt / Vo
(9.81 x 0.780) / 10.7 = 0.7151
θ = sin^-1 (0.7151) = 45.65 degrees