Finding force exerted by a rope and ratio of tension:weight

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SUMMARY

The discussion centers on calculating the force exerted by a rope on a 72.8 kg ice skater moving in a circular path with a radius of 0.765 m at a speed of 5.01 m/s. The calculated centripetal force (Fc) is 2.3886108 kN, derived using the formula Fc = mv²/R. The confusion arises in determining the ratio of this tension to the skater's weight, which is calculated as W = mg, resulting in 710.64 N. The correct ratio requires both forces to be in the same units, leading to a final ratio of 0.003348.

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Homework Statement



A 72.8 kg ice skater is moving at 5.01 m/s when she grabs the loose end of a rope, the opposite end of which is tied to a pole. She then moves in a circle of radius 0.765 m around the pole.

The acceleration of gravity is 9.8 m/s2 .
Find the force exerted by the rope on her arms.
Answer in units of kN = 2.3886108 kN

Find the ratio of this tension to her weight.

Homework Equations



Fc = mv^2 / R
W=mg

The Attempt at a Solution



Fc = mv^2 / R
Fc = (72.8)(5.01)^2 / .765
Fc = 2388.6108 N
Fc = 2.3886108 kN

It's the ratio that's getting me, shouldn't it just be:
2.3886108 kN / (72.8 x 9.8)
=.003348

But the ratio is wrong?

Please help.
 
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The ratio is a comparison of two forces. But they must be in the SAME units!
 

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