A box of mass 22 kg must be raised 1.3 m.
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 mass must be raised . One way is to lift it straight up. The other is to push it along a smooth slope long that rises . ()
- Find the work done against gravity each way.
- Find the force needed each way.
Need a reminder? The key ideaShow
Lifting at a steady speed needs a force equal to the weight , so with . Only the height counts, not the path. Pulling along level ground at a steady speed: , with the friction force.
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) Both ways: .
Step 2. (b) Straight up. The force is the weight: .
Step 3. (b) Slope. , so .
Answer: both ways; straight up, along the slope. The slope needs a quarter of the force, over four times the distance.
Discussion (0)
Log in to join the discussion.
Loading…