Centripetal Force: Calculate Tension for 35kg Boy

[bfr]

Homework Statement

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?

Homework Equations

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

The Attempt at a Solution

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

The correct answer is supposed to be 388 though.

 

[mgb_phys]

Remember there is also the weight of the boy

 

[bfr]

Oh...yeah...thanks! That does it. 45+35*9.8=388.