Work Done by Weightlifter and Barbell

What is the work done by the weightlifter on the barbell and the work done by the barbell on the weightlifter?

Answer:

The work done by the weightlifter on the barbell (WW) is positive, while the work done by the barbell on the weightlifter (WB) is negative.

When a weightlifter lifts a heavy barbell from the floor to a position above her head, the work done by the weightlifter on the barbell (WW) is positive, indicating that the weightlifter is exerting a force in the direction of displacement and transferring energy to the barbell.

Simultaneously, the work done by the barbell on the weightlifter (WB) is negative. This means that the barbell is exerting a force in the opposite direction of the displacement and transferring energy away from the weightlifter. This is due to the fact that the weightlifter's body is being pushed down against the force of gravity as she lifts the barbell upwards.

In summary, the work done by the weightlifter on the barbell (WW) is positive, while the work done by the barbell on the weightlifter (WB) is negative.