# Solving Phase Change & Spatial Separation with Wavelength & Velocity

• kgal

## Homework Statement

A wave of wavelength 75 cm has velocity 375 m/s.
a. What is the spatial separation between two points that are 30° out of phase at a particular time?
b. What is the phase change at a particular position for a time change of 0.5 ms?

u = λ / T

## The Attempt at a Solution

a. I did not understand what the term "spatial separation" meant so I tried to use logic to understand it. The way I defined it was the distance (or Δx) between two points with Δδ = 30°. I understood that one cycle of the wave is 0.75 m and 360°. I didn't know whether the velocity changes at any point of the wave trajectory so I assumed it was constant throughout the propegation. So what I did was divide 360 / 30 = 12. I then divided the the wavelength by the 12 30° parts of the wave and got 0.75 / 12 = .0625 m. Not sure if that is the correct answer but unit-wise it made sense to me.

b. I used the formula u = λf and solved for f = u/λ = 500 Hz .
then calculated δ = 360° * f * Δt = 360*500* (5*10^-4) = 90°.
Not sure its right.

Looks good to me!