Question

Your tennis ball rolls off a 0.91m tall table and hits 0.25m out from the table. What is it's time in the air? What is its vertical velocity before hitting the ground (show work)

Answer 1

consider the motion of the ball in vertical direction after it rolls off the table

v₀ = initial velocity of the ball in vertical direction = 0 m/s

a = acceleration = acceleration due to gravity = 9.8 m/s²

Y = vertical displacement = height of the table = 0.91 m

t = time spent in air by the ball

Using the kinematics equation

Y = v₀ t + (0.5) a t²

0.91 = 0 t + (0.5) (9.8) t²

t = 0.43 sec

v = final velocity in vertical direction just before it hits the ground

Using the kinematics equation

v = v₀ + at

v = 0 + (9.8) (0.43)

v = 4.21 m/s