Asoccer player takes a free kick from a spot that is 20 m from the goal. the ball leaves his foot at an angle of 38 ∘, and it eventually hits the crossbar of the goal, which is 2.4 m from the ground. at what speed did the ball leave his foot?

17.6 N

Explanation:

The force exerted by the punter on the football is equal to the rate of change of momentum of the football:

where

is the change in momentum of the football

is the time elapsed

The change in momentum can be written as

where

m = 0.55 kg is the mass of the football

u = 0 is the initial  velocity (the ball starts from rest)

v = 8.0 m/s is the final velocity

Combining the two equations and substituting the values, we  find the force exerted on the ball: