Question

A stone is dropped from top of a cliff reaches ground level in 4s and then buries itself into 0.8 m of mud. Calculate : height of cilff

Answer 1

Answer:

77.6 m

Explanation:

on analysing, we get that that we have to find height of cliff,

v =u- gt (v=0m/s)

=> 0 =u -9.8*4

=> -u = -39.2 m/s

=> u= 39.2 m/s

here, we get u = 39.2 m/s

Total distance S = height of cliff (h) + 0.8m.

Now,

S=( v^2-u^2)/2g

= u^2 /2*9.8

= (39.2)^2 /19.6

= 1536.64/19.6

= 78.4 m

then, h= (78.4-0.8)m = 77.6 m