please show step by step work thank you 5 A 05kg ball is dr

please show step by step work thank you !

5. A 0.5-kg ball is dropped from a third- story window which is 20 m above the sidewalk. What is the speed of the ball just before it strikes the sidewalk? (A) 5 m/s (B) 10 m/s (C) 14 m/s (D) 20 m/s (E) 200 m/s

Solution

a)

lose in PE = gain in KE

=> mgh = 1/2mv^2

=> V = sqrt ( 2*9.8*20) = 19.798 m/s

option D

B)

power = work/time = 500*9.8*30)/(120 = 1225 Watt

option B