Atennis ball is thrown straight up with an initial speed of 20.5 m/s. it is caught at the same distance about ground as it is thrown.

21.4 m

Time in air = 2 x 2.09 = 4.18 s

Explanation:

v(f)² = v(i)² + 2as  

Take up as positive direction  

0 = 20.5² - 2 * 9.8s  

s = 21.4 m  

So the ball rises to 21.4 m  

(b) v(f) = v(i) + at  

0 = 20.5 - 9.8t  

t = 2.09 s [this is the time to max height]  

Because the ball returns to exactly the same height from which it was thrown, time up = time down  

So time in the air = 2 x 2.09 = 4.18 s