# Power Supplied to a vibrating string

1. Feb 28, 2013

### Willjeezy

1. The problem statement, all variables and given/known data
I keep getting the wrong answer for this question:

A taut spring for which μ = 0.05 kg/m is under tension of 80.0N. How much power must be supplied to the string to generate sinusoidal waves at a frequency of 60Hz and an amplitude of 6cm?

2. Relevant equations
ω = 2∏f
v = √(T/μ)
P = (1/2)μω2A2v

3. The attempt at a solution
Convert cm to m --> 6cm = 0.06m

Find ω
ω = 2∏(60)
= 376.99

Find v
v = √(80/.05)
=0.4m/s2

Find P
P = (1/2)(0.05)(376.99)2(0.06)2(0.4)
=5.12

however, the book tells me the answer is 512W. Did I convert something wrong?

Watts is J/s, and joules is in (Kg * m2)/s, so it only makes sense that I would have to convert the cm to m.

By dimensional analysis my answer has the units of :
(kg * rad2 * m2) / s3

Last edited: Feb 28, 2013
2. Feb 28, 2013

### TSny

Check this part of your calculation.

3. Feb 28, 2013

### Willjeezy

blah....thanks.