Zain is standing on a bridge. He tosses a ball upwards, which rises, stops, and then falls all the way to the water (30 meters below Zain). Suppose that the speed at which Zain tosses the ball 1.50 m/s, and then answer the following two questions.

(A) How much time does it take the ball to strike the water?

(B) What is the speed of the ball when it hits the water?

A. 2.41 s.

B. 24.3 m/s.

Explanation:

vf = vi + 2a*t

where, vf = final velocity

= 0 m/s

vi = final velocity

= 1.5 m/s

a = 9.8 m/s^2

A.

ti = 1.5 / (9.8 * 2)

= 0.08 s

Vf^2 = Vi^2 + 2a*s

1.5^2 = 2 * 9.8 * s

S = 0.115 m

Time taken to drop into the water,

30.115 = 1.5*to + 4.9*to^2

to = 2.33 s

Total time taken = ti + to

= 2.33 + 0.08

= 2.41 s.

B.

Vo = 0 m/s

S = 30.115 m

Vf = ?

Using,

Vf^2 = Vo^2 + 2*a*s

= sqrt (2*9.8*30.115)

= 24.3 m/s.