# PHY C14: Wave Motion

We’re covering:

• Progressive Waves
• What is wave motion?
• Components of wave motion
• Wave equation

Let’s go!

What is Wave Motion?
Propagation of disturbances which carries energy without transferring matter.

What causes Wave Motion?
Vibrations (oscillations).
The energy from these oscillations propagates through waves.

Wave motion can be observed as:

This chapter will deal with progressive waves.

Waves can also be classified into:

See here for more.

Examples of Wave Motion:
There are 2 major groups:

Components of Wave Motion

Representing Phase Difference

The red particles are at different points in their cycle at any moment in time.
The motion of each particle can be graphed against time.

Calculating Phase Difference:

Next, we will look at the wave equation describing speed:
v = fλ

How is the wave equation derived?
Wavelength is the distance travelled by a wave in one cycle: λ

Frequency is the number of cycles per second:
f = 1/T

Speed is distance travelled per second:
v = λ/T

Therefore:
v = fλ

*Remember:
Velocity is the SAME in the SAME MEDIUM.
Two water waves might have different f & thus λ, but they will have same v.
Two sound waves in air travel at the same speed: 343 ms-1