# Homework Help: Determining Wave Equation

1. Nov 6, 2013

### thatguy14

1. The problem statement, all variables and given/known data
One end of a long horizontal string is attached to a wall, and the other end is passed over a pulley and attached to a mass M. The total mass of the string is M/100. A Gaussian wave pulse takes 0.12 s to travel from one end of the string to the other.

Write down the equation for the displacement of
the string as a function of position and time.

2. Relevant equations
Y = Aexp(-(x-vt)^2/a) - equation of Gaussian waveform

3. The attempt at a solution

Hi I am actually totally lost on how to find the parameters A and a. Find v is pretty easy using the tension and mass/length and speed. I have no clue where to start on finding A and a.

Thanks!

2. Nov 10, 2013

### BruceW

hmm. that's strange. So they did not give you 'a' ? I don't think you can calculate the width of the Gaussian, if they do not give it to you. I mean, the width could take on any value. Also, it's not a true Gaussian wave pulse, because it does not extend to $\pm \infty$ (since there are boundaries). But I guess as long as the width of the Gaussian is a lot smaller than the length of the string, then it will look roughly like a Gaussian wave pulse.