Answer:
3.56 s
Explanation:
To find the time the rock fell, we can just analyze the vertical motion of the rock, which is a free fall motion. So we can use the suvat equation
[tex]s=ut+\frac{1}{2}at^2[/tex]
where
s is the vertical displacement
u is the initial vertical velocity
a is the acceleration
t is the time
In this problem, taking downward as positive direction:
s = 62 m (height of the cliff)
u = 0 (the rock is thrown horizontally, so no vertical velocity)
[tex]a=g=9.8 m/s^2[/tex] (acceleration of gravity)
Solving for t, we find
[tex]t=\sqrt{\frac{2s}{a}}=\sqrt{\frac{2(62)}{9.8}}=3.56 s[/tex]
