Question

F a ball with an original velocity of zero is dropped from a tall structure and it takes 7 seconds to hit the ground, what velocity does the ball have
when it reaches the ground? A. 34.3 m/s B. 68.6 m/s C. 156.8 m/s D. 240.1 m/s

Answer 1

For this, all you need is the velocity formula which is Vf = Vi + at.
Vf = final velocity.
Vi = initial velocity.
a = acceleration
t = time

Vf = Vi + at. 

Vf= 0 + (- 9.8 m/sec^2) (7s)

*The 0 says that the original velocity is zero. The - 9.8 m/sec^2 is gravity because there is nothing else acting upon it, and it is negative because it is falling. The 7s is time time.*

All you have to do then, is simplify to get 68.6 m/s which is B.