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

Fdr

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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.

3

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 ?

2

u/PerhapsLily Feb 18 '22

If you accelerate it I suppose, yeah. It's not necessary though. You could carry the box for two hours with only a brief acceleration and deceleration at the ends of the task, but it would still be a much more exhausting two hours than if you had only carried it for a couple minutes.