# physics

A horizontal force of 210 N is exerted on a 2.0 kg discus as it rotates uniformlyin a horizontal circle (at arm’s length) of radius 0.90 m. Calculate the speed of the discus.

is the answer 9.7

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asked by joo
1. centipetal force=holding force.

mass*velocity^2/radius=210
solve for velocity

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2. The question sdoes not make clear whether the force is centripetal, tangential or a combination of both. In an actual discus throw that is well done, the thrower pushes the discus at an increasing speed while spining around in approximatly one complete circle. If the accelerating tangential force is the force they are talking about, then a different speed will be obtained than one would by treating it as a centripetal force problem, for which Force = M V^2/R.

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posted by drwls

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