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Chapter 9: Q. 3 (page 227)

An elevator held by a single cable is ascending but slowing down. Is the work done by tension positive, negative, or zero? What about the work done by gravity? Explain.

Short Answer

Expert verified

Tension is doing positive work while gravitational force (gravity) performs negative force

Step by step solution

01

Given Information

An elevator held by a single cable is ascending but slowing down.

02

Explanation

We know that the positive work is done when direction of force and displacement is in the same direction.

Tension in the cable is acting upwards and the movement of the elevator is upwards.
As the force (tension) and displacement are in the same direction, so the work done by the tension is positive.

Now consider gravity,
Since the gravitational force and movement are in the opposite directions, so the work done by the gravity is negative.

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