A 0.25 kg phone drops off a table and falls with a velocity of 0.55 m/s and strikes a 0.75 kg book and bounces back with a velocity of 0.1 m/s. What is the velocity of the book after the phone strikes it?

Question

Quizplus · Accepted Answer

Use the following formula to calculate the book's velocity.
m1v1 + m2v2 = m1v1' + m2v2'
Once you plug in the values from the word problem, you would have:
(0.25 kg)(0.55 m/s) + (0.75 kg)(0 m/s) = (0.25 kg)(0.1 m/s) + (0.75 kg)v2'
0.14 kg m/s + 0 m/s = 0.025 kg m/s + (0.75 kg)v2'
0.14 kg m/s - 0.025 kg m/s = (0.75 kg)v2'
0.115 kg m/s = (0.75 kg)v2'
v2' = (0.115 kg m/s) / 0.75 kg
v2' = 0.15 m/s

A 025 Kg Phone Drops Off a Table and Falls with with a Velocity