A stone falls freely from rest for 8.0s.

Question

A. Calculate the stone's velocity after 8.0s.

V2-V1+at
V2 = (0) = 9.8(8.0)
V2 = 78.4m/s

B. What is the stone's displacement during this time?

d = (v2 + v1)t/2
d = (78.4 + 0)/2(8.0)
d = 313.6m

Answer 1

You seem to be mixing up your = and - signs in the first two equations. Those were probably just typing errors.

I agree with your answers.