Question

A heavy object is dropped from a vertical height of 8.0 m. What is its speed when it hits the ground?

Answer 1

What do you know:
d=-8.0mm (starts higher and ends lower so it is negative)
Vi=0m/s (because it was dropped, not thrown)
A=-9.8m/s^2 (gravity)
Vf=???
Use the equation:
Vf^2=Vi^2+2A(d)
Vf^2=2(-9.8)(-8.0)
Vf^2= 156.8 -->find the square root of this
Final answer: Vf= 12.5m/s