# Homework Help: Analyzing a wave

1. Sep 2, 2007

### aliaze1

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

http://photo.ringo.com/230/230997145O975467146.jpg [Broken]

http://photo.ringo.com/230/230997145O975467146.jpg [Broken]

2. Relevant equations

λ=v/f
k=2π/λ
ω=2πf
T=1/f
v=ω/k
V(string) = √(Tension of string/μ), where μ = denisty

D(x,t) = A sin (kx - ωt + Φ)

3. The attempt at a solution

I found the maximum displacement as 2, found from the given equation

The third part seemed to be the next simplest, so using v=ω/k, I calculated 638/12.57 as the speed, which was incorrect

To my knowledge, this speed is needed to calculate the tension of part 1

Last edited by a moderator: May 3, 2017
2. Sep 2, 2007

### Astronuc

Staff Emeritus
3. Sep 2, 2007

### aliaze1

i guess it is possible, but that is the exact question copied word-for-word

4. Sep 2, 2007

### rootX

what does d(D(x,y))/dt means?

5. Sep 23, 2007

### aliaze1

I just realized that the third part is not required to complete the first part,

using v=ω/k, and plugging this v into

V(string) = √(Tension of string/μ), where μ = denisty;

I get an answer of 12880.7, which is essentially 12.9 *103....the answer however is simply 12.9....

where am i going wrong?

thanks

6. Sep 23, 2007

### aliaze1

I thought it had to do with the amplitude being in centimeters, so I divided by 100, but that still is 129 not 12.9...

7. Sep 23, 2007

### Astronuc

Staff Emeritus
Make sure all units are consistent. The linear mass density is 5 g/ m as opposed to 0.05 g /cm or 0.005 kg/m. Perhaps that is where one is off by 3 or 1 order of magnitude depending on the values one uses. Tension should be in Newtons (for SI/mks).

Last edited: Sep 23, 2007
8. Sep 23, 2007

### aliaze1

thanks!, makes sense