What Is the Correct Velocity of the Standing Wave?

[Spirochete]

Homework Statement

The standing wave in the picture is oscillating at 100 Hz. What is it's velocity?

Homework Equations

Velocity=(wavelength)(frequency)

I believe is the equation that applies here.

The Attempt at a Solution

The wavelength from the picture appears to be 20x10-2 meters.

So velocity should equal (20x10-2)(100)= 20 meters per second

But I know this answer is wrong. Where am I going wrong?

 

[berkeman]

Homework Statement

The standing wave in the picture is oscillating at 100 Hz. What is it's velocity?

Homework Equations

Velocity=(wavelength)(frequency)

I believe is the equation that applies here.

The Attempt at a Solution

The wavelength from the picture appears to be 20x10-2 meters.

So velocity should equal (20x10-2)(100)= 20 meters per second

But I know this answer is wrong. Where am I going wrong?

Why do you say that the wavelength is 20cm? Draw a full cycle of a sine wave -- what does it look like?

Also, be careful with your units. It looks like you are mixing cm and meters in your multiplication and answer...?

 

[thomate1]

Your attempt at a solution is correct, but the units are incorrect. The wavelength should be in meters (m) and the frequency should be in Hertz (Hz). So the correct equation is velocity = wavelength x frequency, which in this case would be (0.20 m)(100 Hz) = 20 m/s. The key is to make sure that your units are consistent throughout the equation.