A boy whirling a rope above his head with a stone tightened at the end of it. The boy whirled it with a speed of 18 m/s and a period of 2.0 s/rev. (a.) find the lenght of the rope. (b.) find its centripetal acceleration (c.) if the stone has a mass of 6g, how much centripetal force is acting on it?

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espex · Answer

$$v=2\pi r/T$$ So to find the length of the rope you solve for r. $$a=v ^{2}/r$$ Use previous results to find acceleration. Finally you have F=ma to calculate force.