Question

https://youtu.be/aZw39031PvkA. Is the weightlifter using energy? How do you know?B. Where is the weightlifter using the most energy - while lifting the weights, or while holding the weight overhead? What makes you think this?C. A physicist would say that the weightlifter is doing no work while holding the weights overhead. Do you agree with this? Why or why not?

Answer 1

A. Yes, he is using energy. You know it because he lift the weight, when an object with mass m is lift a height h and has a garvity g, then you get potential energy. PE=mgh

B. When is lifting the weight, because he has to accelerate the object and move it, changing his speed and his height, kinetic and potential energy.

C. Thats correct, because there is not change in the distance, only is applying a force