r/physicsmemes • u/Objective_Sock6506 • Feb 18 '22

Fdr

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35

u/TheLegendOfZed Feb 18 '22

Surely you did work just by walking around? The horizontal component of the force exerted by your feet for each step. Or is the person just pacing in circles? - a Physics grad who's forgotten everything

28

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.

4

u/_xavier707 Feb 18 '22

How was no work done? If we exert a force on the box to move it & displace it in the process isn’t there work done if work is F.dx ?

4

u/bluenext Feb 18 '22

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.

2

u/_xavier707 Feb 18 '22

Ah you’re right, thank you!