omg plzz help me plzz physics?

Question

A ball of mass 0:4 kg, initially at rest, is
kicked directly toward a fence from a point
20 m away, as shown below.
The velocity of the ball as it leaves the
kicker's foot is 17 m=s at angle of 51 ± above
the horizontal. The top of the fence is 7 m
high. The kicker's foot is in contact with the
ball for 0:04 s. The ball hits nothing while in
°ight and air resistance is negligible.
The acceleration due to gravity is 9:8 m=s2




What is the vertical component of the velocity
when the ball reaches the plane of the fence?
Answer in units of m=s.

Answer 1

First we want to know the vert and hor components of initial velocity v0. Then hor vel and distance give us the time, then time and g give us velocity.
v0x (hor) = v0cos(theta)
v0y (vert) = v0sin(theta)
flight time to plane of fence t = x/v0x
vy(t) = v0y - gt
Note that the height of the fence and the mass of the ball are irrelevant, but it may make your day to know that the ball cleared the fence.