# Homework Help: Waves in wires/strings

1. Aug 3, 2008

### skiing4free

1. The problem statement, all variables and given/known data
I have been writing up a Physics Experiment with working out the speed of waves in a wire.
The wire is stretched across two points which send vibrational pulses down the wire. I am stuck with working out the Mass of the wire throw theoretical methods? hope anyone can help.....

2. Relevant equations
Wave speed=122ms-1
Tension=3.13N1/2
Length=.9m
Mass of length=?

Wave speed=(tension T/mass per unit length)1/2

3. The attempt at a solution
My answer mass=.21029gm^2, just not sure if this is right, it sounds to light for the length of the wire. hope anyone has any ideas ;)

2. Aug 3, 2008

### Integral

Staff Emeritus
You need to pay better attention to your units. How could the wire have a mass in g 2? is not mass just grams? Also in your post you give the Tension in N 1/2 ??? What is that?

All you need do is solve your given expression for mass per unit length. This quantity will have units of $\frac {kg} m$. Then multiply by your length to get a result in kg.

3. Aug 3, 2008

### skiing4free

right I see what you mean, sorry about N 1/2 i meant the tension is in newtons to the power of a half, but i understand why i went wrong, thanks for the help. Cheers Intergral