Waves

Wavelength (λ)

Distance between two identical points

Frequency (f)

Number of waves per second (Hz)

Amplitude

The heigh of a wave from the peak of the wave to the equilibrium

time Period

Time for one wave to pass a point ( measured in secs)

🔹 Mass

Amount of matter

Measured in kg

Does NOT change with location

🔹 Weight

Force caused by gravity

Measured in Newtons (N)

Changes depending on planet

weight equation

W=mg g = 9.8 N / g

wave equation

v=fλ

Transverse

Vibrations at right angles of energy travel Example: Light waves

Longitudinal

waves vibrating in the direction of energy travel Example: Sound waves

Sound Waves

Sound is a longitudinal wave Travels through solids, liquids and gases Cannot travel through vacuum

🔹 Speed of Sound

• Air ≈ 340 m/s

• Faster in solids

• Slowest in gases

pitch

frequency

loudness

amplitude

echos

An echo is a reflection of a sound wave.
Sound hits a surface → bounces back → you hear it again.

why dont echos always occur

To hear a separate echo:

• The reflected sound must arrive at least 0.1 seconds later

• Otherwise it just sounds like one sound

This is because your brain can’t separate sounds closer than 0.1 s apart.

echo equation

Distance= vt​ / 2 ( v = speed of sound 340 m / s in air t = time for echo e.g 2 secs)

why would u divide it by 2

Because the time measured is:

• going to the wall

• coming back

The distance you want is only one way.