A rock falls off a cliff and hits the ground after 6 seconds. What is its velocity right before it hits the ground?

A).31 m/s

B) 3.3 m/s

C) 29.4 m/s

D) 9.8 m/s

The equation: Vf = Vi + at should answer this question, where:

Vf = Unknown

Vi = 0

a = acceleration = 9.8 m/s^2

t = 6 seconds

Plug values in:

Vf = 0 + 9.8*6

Vf = 58.8 m/s

I noticed that this is not on your list of answers, which means that some value from your problem is incorrect. I would double check that.