Aperson steps off the end of a 3.45 � high diving board and drops to the water below. (a) how long does it take for the person to reach the water? (b) what is person’s speed on entering the water? (c) what is person’s speed on entering the water if they step off a 12.0 � diving

(a) 0.84 s

(b) 8.22 m/s

(c) 15.33 m/s

Explanation:

u = 0 , h = 3.45 m, g = 9.8 m/s^2

Let time taken to reach the water is t and the velocity at the time of hitting of water surface is v.

(a) Use first equation of motion

s = u t + 1/2 a t^2

3.45 = 0 + 0.5 x 9.8 x t^2

t = 0.84 second

(b) Use first equation of motion

v = u + a t

v = 0 + 9.8 x 0.84 = 8.22 m/s

(c) If h = 12 m

use third equation of motion

v^2 = u^2 + 2 g h

v^2 = 0 + 2 x 9.8 x 12

v = 15.33 m / s