The Rubber Bands

QUESTION:

drawing of a pulley system

Two identical rubber bands connect masses A and B to a string over a frictionless pulley of negligible mass. The amount of stretch is greater in the band that connects which mass?

A
B
A and B are the same.

ANSWER: C

The tension that stretches the rubber bands is the same as the tension in the string—the same at both ends, in accord with Newton's 3rd law.

To better see this, imagine the rubber bands are farther from the ends of the string. If the tension all along the string is the same, likewise for the rubber bands.

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