# Homework Help: Kicking a ball ( optimal angle)

1. Apr 13, 2012

### mahrouqi

A ball is kicked with a speed of 7.5 m/s and an angle  (relative to the horizontal) of
(a)  = 45, (b)  = 40.

The ball lands on a flat area 5 m lower than the place where it was kicked.
First describe how you choose your coordinate system (frame of reference): origin and
directions of axes used; and state the equations you apply to answer the questions below.

For both cases
(i) calculate the time the ball is flying,
(ii) determine the highest point (how high above the start),
(iii) calculate the horizontal distance it was flying
(iv) In class we found that the optimal angle for the horizontal distance is  = 45 in a
similar but di erent problem. Explain why your result here is not in contradiction to that
finding. for the problem we did it in the class y initial was equal to y final but i am not sure if this is the answer i didnt get the question !!

(v) Repeat (i) { (iii) in the case when the
at area for landing is 1 m higher. What changes
qualitatively?

2. Apr 13, 2012