Solution
In this question we have given
time,t = 3 s
here rock is falling from a cliff, Therefore, in this case gravitational acceleration will act on rock which is g=[tex]9.8\frac{m}{s^{2} }[/tex]
Let s be the height of cliff
here, initial velocity of rock,u=0
we know from second equation of motion
[tex]s=ut+.5at^{2}[/tex]............(1)
here a=g=[tex]9.8\frac{m}{s^{2} }[/tex]
put values of u,t and a in equation (1)
[tex]s=0+.5\times9.8\frac{m}{s^{2} } \times3^{2}s^{2}[/tex]
[tex]s=44.1m[/tex]
therefore, height of the cliff is 44.1m
