# Homework Help: A question about string tension

1. Aug 1, 2011

### Carnivean

1. The problem statement, all variables and given/known data

The A string on a violin has a fundamental frequency of 440Hz.
The length of the vibrating portion is 31.2cm and has a mass of
0.355g. Under what tension must the string be placed? (Find the
answer in the usual metric unit of tension, the Newton, but do not enter
units)

2. Relevant equations

square root of Tension/(mass/length) = velocity of string.

Velocity = frequency X wavelength

3. The attempt at a solution

Soo.... V = square root OF Tension/ (.355g/.321 m) (or do I need to convert grams to kilograms?)

So to find velocity i was thinking V = frequency X wavelength. So... (440Hz X .642) which is 282.48..

So velocity = 282.48? then that would mean that 282.48 = squareroot of Tension/ (.355g/.321 m) ?

Am I on the right track?

2. Aug 1, 2011

### Pi-Bond

Always keep an eye on units. Since you need tension in Newtons, you mass always needs to be in kilograms (1 Newton is equal to 1 kg.m.s-2)