A 0.40 kg block on a smooth table is pushed against a spring with k = 250 N/m, squeezing it 12 cm…
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 on a smooth table is pushed against a spring with , squeezing it , and let go. How fast does the block leave the spring?
Need a reminder? The key ideaShow
When only conservative forces (gravity, springs) do work, mechanical energy is conserved: . Forces that do no work, like a smooth surface's push or a string at right angles to the motion, do not spoil it.
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. , , .
Plan. Conservation of energy.
Step 1. Spring energy. .
Step 2. Speed. .
Answer: .
Check. , the spring's energy. Good.
Watch out. The speed is proportional to the squeeze, not to its square: twice the squeeze gives twice the speed (and four times the energy).
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