Question

A ball is dropped from a cliff and falls a distance of 20 m to the ground. Determine the velocity it hits the ground at and the time for the ball to fall.
A.v = -10 m/s, t = 2 s
B.v = 20 m/s, t = 4 s
C.v = -20 m/s, t = 2 s
D.v = 10 m/s, t = 2 s

Answer 1

Use the kinematic equation: d = vi • t + ½ • a • t^2
20=0(t)+(0.5)(9.8)(t^2)
20=4.9(t^2)
t=2.02seconds
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Final Velocity=Initial Velocity +at^2
Vf=(9.8)(2.02^2)
Vf=19.796