Question

A rock is released from rest and freely falls 70 m to the ground. What is its velocity just before impact? A. 1.2 m/s B. 7.0 m/s C. 9.8 m/s D. 12 m/s​

Answer 1

Answer:

37.04 m/s

Step-by-step explanation:

we can use the equation x = x0 + v0t + 1/2at^2

a = -9.8 m/s^2, the acceleration due to gravity

x0 = 70 m, the starting point of x

v0 = 0 m/s

x = 0

this will allow us to solve for time

0 = 70 + 0 +-4.9t^2

t = 3.779

now we can use the equation v = v0 + at

v = 0 + 9.8(3.77)

v = 37.04 m/s