Afootball kicker is attempting a field goal from 44 m from the goal post. the ball is kicked and just clears the crossbar 2.9 s later. if the angle of the kick was 45°, what was the initial speed of the ball? a. 39 m/s b. 19.7 m/s c. 2.2 m/s d. 21.6 m/s

D. 21.6 m/s

Explanation:

This problem is a projectile motion problem, where we know that the ball reaches a horizontal distance of x=44 m in a time of t=2.9 s. We also know that the ball was kicked with an angle of .

We are only interested in the horizontal motion of the ball, which is a uniform motion with constant speed , where is the initial speed of the ball. The horizontal velocity is simply equal to the ratio between the horizontal distance and the time:

Re-arranging the equation, we find

So, the best answer is

D. 21.6 m/s

potential energy is directly proportional to height.

more height = more potential energy.

greatest increase in height = greatest increase in potential energy

where are the points with the greatest increase in height ?

has to be c-e or d-e .