Question

A cricket ball is dropped from a height of 20 metres.
(a) Calculate the speed of the ball when it hits the ground.
(6) Calculate the time it takes to fall through this height. (g = 10 m/s)​

Answer 1

Answer:

(a)v^2=u^2+2as (here a =g)

0=u^2+2*-10*20

thus u^2=400

u=20 m/s

(b)v=u+at

V=u-gt

0=20-10t

therefore t=2 seconds

Answer 2

Answer:

Explanation:

Since given u=0,v=?,g=a=10m/s²

So using third equation of motion:

V²=u²+2as

V²=0+2*20*10

V²=400

V=20m/s

Now using first equation of motion:

V=u +at

20=0+10*t

T=20/10=

T=2second