A box of weight 55 N slides 7 m on a level floor.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A box of weight slides on a level floor. The friction force on it is . Find the work done on the box by
- friction;
- its weight.
Need a reminder? The key ideaShow
Work when an object moves a distance along a steady force ; . The work is positive when the force is along the motion, negative when it is against it, and zero when it is at right angles or nothing moves.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Friction is against the motion: .
Step 2. (b) The weight is down and the box moves along the floor, at right angles to it: .
Answer: ; .
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