Answer:
V = -39.2m/s
Step-by-step explanation:
Given the following data
Time, t = 4secs
Since the rock is falling, we know that the initial velocity = 0
Acceleration due to gravity = 9.8m/s²
To find the final velocity, we would use the first equation of motion
V = U + at
Substituting into the equation, we have
V = 0 + (-9.8*4)
V = -39.2m/s