Practice question · Multiple choice
Carrying a heavy box horizontally at constant speed does no work in the physics sense, though you tire. Why does the definition exclude it?
Hints
- Ask what happens to the box’s energy during the walk.
- The dot product is doing the work here, so to speak.
Show the answer
D. Because the upward force is perpendicular to the motion
Why
The box’s kinetic and potential energy are unchanged, so no work was done ON IT. Your fatigue is real and internal, physiological cost is not mechanical work.
Practise Work, Energy, and the Work-Energy Theorem
The app has 8 more questions on this lesson, and keeps your place in the course. Physics I is free to start.