A 40-kg skater moving at 4 m/s overtakes a 60-kg skater moving at 2 m/s in the same direction and collides with her. The two skaters stick together. (a) What is their final speed? (b) How much kinetic energy is lost?
(a)

The final speed of the system.
Answer to Problem 56E
The final speed of the system is
Explanation of Solution
Given info: Mass of the first skater is
Write the expression from conservation of momentum.
Here,
Substitute
Conclusion:
Therefore, the final speed of the system is
(b)

The amount of kinetic energy lost.
Answer to Problem 56E
The amount of kinetic energy lost is
Explanation of Solution
Given info: Mass of the first skater is
Write the expression for kinetic energy lost.
Here,
Substitute
Conclusion:
The amount of kinetic energy lost is
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Chapter 3 Solutions
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