# Writing an equation for a wave

1. Aug 10, 2008

### rugapark

I needed to write an equation for a wave with:

amplitude : 2cm
wave vector : 502.7
angular frequency : 125.7 Hz
time : 0 sec

and I used the general equation for waves to come up with:

y = 0.02 sin (125.7 - 502.7x)

is that alright?

2. Aug 10, 2008

### CompuChip

What is the general equation you used (and what do the constants mean)?

Also, what do you mean by: wave vector = some number ?

3. Aug 10, 2008

### rugapark

y=A sin (wt$$\pm$$kx) is the formula where

A = amplitude
w = angular freq.
t = time
k = wave vector

wave vector doesnt have units as it's a vector quantity.. right?

4. Aug 10, 2008

### Barny

You might want to reconsider this statement. Displacement is a vector quantity, would you agree that displacement has a unit?

One hint - the argument of the Sine function must be dimensionless.

I agree with your general equation. However, using the conditions you gave (t=0) are you sure that you're happy with the time component of the argument? Remember your multiplying the angular velocity and time, with the time equal to zero. Are you sure this would give you the angular velocity back, like your expression suggests?

Kind Regards

Barny

5. Aug 10, 2008

### Chrisas

What's given for frequency is Hz, usually represented by f. The radian frequency, w, is w=2*pi*f. However, the wave equation has w*t. If t is zero, then that product is zero, and there is no need to convert.