Question

A rock falls (vi=0) from the top of a 128 m cliff to the ground below.

How long does it take for the rock to fall?

Answer 1

5.11 s

Step-by-step explanation:

Given:

v₀ = 0 m/s

y₀ = 128 m

y = 0 m

a = -9.8 m/s²

Find: t

y = y₀ + v₀ t + ½ at²

(0 m) = (128 m) + (0 m/s) t + ½ (-9.8 m/s²) t²

t = 5.11 s