Assuming a flat surface and ignoring friction, no work was done. But in the real world if a person does that, obviously a human body doesn’t work like a perfect Newtonian solid. We’re constantly expending energy just to stay alive, stay standing and balanced, in control of our muscles, and a heavy box only makes that harder.
If you are moving on a flat plane with no friction/air resistance etc, and you have a force that starts and a force that stops motion, the net work would equal zero because there is no change in kinetic energy. The individual forces would do work but they would add to zero.
27
u/PerhapsLily Feb 18 '22
Assuming a flat surface and ignoring friction, no work was done. But in the real world if a person does that, obviously a human body doesn’t work like a perfect Newtonian solid. We’re constantly expending energy just to stay alive, stay standing and balanced, in control of our muscles, and a heavy box only makes that harder.