Simple Harmonic MotionThe oscillatory- or back and forth- motion of a

pendulum.Can be represented by a sin curveWaves follow the same pattern

Wave Descriptions• The high points on a wave are called crests. • The low points on a wave are called troughs. • The term amplitude refers to the distance from

the midpoint to the crest (or trough) of the wave. • Wavelength is the distance between the crests (or

troughs) of a wave

FrequencyThe number of vibrations an object makes

per unit of timeCan be either the frequency of the vibrating

source causing the wave or of the wave itselfExample: The number of times a crest passes

you in 5 seconds.

Frequency is measured in Hertz (Hz)Represents the number of cycles per second.If one wave passed a given point every

second, it would have a frequency of 1 HzRadio waves are measured to have a

frequency of 960 kHz, which is relatively low

If we know the frequency, we can calculate the period, or vice versa

Suppose, for example, that a pendulum makes two vibrations in one second. Its frequency is 2 Hz. The time needed to complete one vibration—that is, the period of vibration—is 1/2 second.

The energy transferred by a wave from a vibrating source to a receiver is carried by a disturbance in a medium.

It is important to note that the disturbance is what is moving and not the medium itself

Wave speedWave speed depends on the medium that the

wave is traveling throughHowever, no matter what the wave is

traveling through, the wavelength, frequency and speed are related through the equation:

v = fwhere v is wave speed, is wavelength,

and f is wave frequency.

Wavelength and frequency vary inversely to produce the same wave speed for all sounds.

If a water wave vibrates up and down two times each second and the distance between wave crests is 1.5 m, what is the frequency of the wave? What is its wavelength? What is its speed?

What is the wavelength of a 340-Hz sound wave when the speed of sound in air is 340 m/s?

Types of waves

TransverseThe motion of the particles being displaced is

perpendicular to the wave motion

LongitudinalThe motion of the particles is parallel to the

motion of the waves.

InterferenceOccurs when waves from different sources

meet at the same point at the same timeAn interference pattern is a regular

arrangement of places where wave effects are increased, decreased, or neutralized.

In constructive interference, the crest of one wave overlaps the crest of another and their individual effects add together.

The result is a wave of increased amplitude, called reinforcement.

In destructive interference, the crest of one wave overlaps the trough of another and their individual effects are reduced.

The high part of one wave fills in the low part of another, called cancellation

https://www.youtube.com/watch?v=wYoxOJDrZzw

A standing wave is a wave that appears to stay in one place—it does not seem to move through the medium.

• Nodes are the stationary points on a standing wave. Hold your fingers on either side of the rope at a node, and the rope will not touch them.

• The positions on a standing wave with the largest amplitudes are known as antinodes.

• Antinodes occur halfway between nodes.

The Doppler EffectAs a wave source approaches, an

observer encounters waves with a higher frequency. As the wave source moves away, an observer encounters waves with a lower frequency.

View in presentation mod to see waves- No Doppler effect

Doppler effect

Observer Moving:Towards source: add vs

Away from source: Subtract vs

Source Moving:Towards observer: subtract vo

Away from observer: add vo