A ball is kicked with a velocity of 
at an angle of 
to horizontal ground. The ball then strikes a vertical wall at the instant when the path of the ball becomes horizontal, as shown.
Assume that air resistance is negligible.
By considering the vertical motion of the ball, calculate the time it takes to reach the wall.
Explain why the horizontal component of the velocity of the ball remains constant as it moves to the wall.
Show that the ball strikes the wall with a horizontal velocity of 
.
for the ball to reach the wall.
