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bfr
Feb11-08, 05:56 PM
1. The problem statement, all variables and given/known data

A 35kg boy is swinging on a rope 7 m long. He passes through the lowest position with a speed of 3 m/sec. What is the tension in the rope at that moment?

2. Relevant equations

F=ma
F=(m*v^2)/R
v=(2pi*r)/T

3. The attempt at a solution

F=(35*3^2)/7=45N

The correct answer is supposed to be 388 though.

mgb_phys
Feb11-08, 05:59 PM
Remember there is also the weight of the boy

bfr
Feb11-08, 06:11 PM
Oh...yeah...thanks! That does it. 45+35*9.8=388.