# Answer to Question #825 in Mechanics | Relativity for Jordan

Question #825

A rock is dropped from a cliff. Approximately how long does it take to fall 45m if the acceleration due to gravity is 9.8 m/sec^2?

Expert's answer

From the equations of the motion

h=h

we have

h

5 = 9.8 t

t = sqrt (9.18) = 3.03 sec.

Answer: It will take 3 sec to fall.

h=h

_{0}+ v_{0}t +at^{2}/2:we have

h

_{0 }= gt^{2}/2;5 = 9.8 t

^{2}/2;t = sqrt (9.18) = 3.03 sec.

Answer: It will take 3 sec to fall.

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