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A stone of mass 0.15 kg is whirled on a string of length 0.65 m in a horizontal circle, at 4.5 m/s…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A stone of mass is whirled on a string of length in a horizontal circle, at . Ignore gravity's effect on the string.
- What is the tension?
- The string breaks at . At what speed does it break?
Need a reminder? The key ideaShow
A body moving at speed on a circle of radius needs a net force toward the centre:
It is supplied by a real force: tension, friction, a normal reaction or gravity.
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. , , , breaking tension .
Plan. The tension is the centripetal force.
Step 1. Tension. .
Step 2. Breaking speed. .
Answer: (a) . (b) .
Check. The tension goes as . The tension rose times, and the speed times: . Good.
Watch out. When the string breaks, the stone flies off along the tangent, not straight outward.
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