A 3.5 kg block rests on a smooth floor. A steady horizontal pull of 12 N drags it 6.0 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 block rests on a smooth floor. A steady horizontal pull of drags it . How fast is it moving at the end?
Need a reminder? The key ideaShow
Kinetic energy is . The work-energy theorem: the net work done on a body equals its change in kinetic energy, .
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.
Given. , , , from rest, no friction.
Plan. Work-energy theorem.
Step 1. Work. .
Step 2. Speed. , so .
Answer: .
Check. and , so . Same.
Watch out. The energy method gives the speed directly, without the acceleration or the time.
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