Question

A boy drops a ball from a cliff 122.5m high.Find: a) How long does it takes the ball to fall to the ground?
b) How far does it fall in the 1st 3 seconds?

Answer 1

a)s= ut+ 1/2 at^2
here, u= 0. a= 9.8m/s or 10m/s
by substituting the values you'll be able to get the value of t

Answer 2

a.$s = ut + 1 \div2 {at}^{2}$

where s is distance which is 122.5
t is time
a is acceleration which is 9.8 m/s^2
putting the values in the formula
we get
122.5=0×t + 96t^2
t^2=1.28
t=√1.28

b.we use the formula
${v}^{2} = {u}^{2} + 2as$

29.4= 2×9.8×s
29.4=19.6s
s=1.5metres