Answer: 9.9 seconds
Explanation:
that's just how long it takes
A physics student drops a rock from a 55 m cliff, it takes 3.35 seconds to hit the ground.
Solution:
Using the second equation of motion, [tex]s=u t+\frac{1}{2} a t^{2}[/tex]
Where, U= initial velocity of ball
S = distance at which rock is dropped from cliff = 55 m
t = time period
a = acceleration due to gravity = 9.8 m/s
Since the ball is dropped from cliff, initial velocity is zero.
u = 0
[tex]\begin{array}{l}{S=0 \times t+\frac{1}{2} 9.8 t^{2}} \\\\ {55=0+4.9 t^{2}} \\\\ {t^{2}=\frac{55}{4.9}=11.22} \\\\ {t=\sqrt{11.22} \approx 3.35 \text { second }}\end{array}[/tex]
