A Pair of Railway Boxcars Are Moving Toward Each Other

question 21

Multiple Choice

A pair of railway boxcars are moving toward each other on a rail with negligible friction. One boxcar is twice the mass of the other. On collision, the boxcars couple to each other. In order for the coupled pair to have zero velocity (relative to a bystander next to the track) after the collision, what is the ratio of velocities of the more massive to the less massive boxcar before the collision?

• A)1/2
• B)1/3
• C)-1/3
• D)-1/2

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