Wave Types
A disturbance that transfers energy from one place to another.
What is a wave?
Maximum displacement from equilibrium. How big the disturbance is.
What is amplitude?
The relationship that connects wave speed, frequency, and wavelength.
What is v=fλ?
A point on a standing wave that does not move.
What is a node?
You shake a rope up and down. The wave travels along the rope.
What kind of wave is this? (transverse)
Particles move perpendicular to the direction the wave travels. Crests and troughs.
What is a transverse wave?
Distance from one crest to the next crest (or one compression to the next).
What is wavelength (λ)?
A wave has a frequency of 5 Hz and a wavelength of 2 m. What is its speed?
What is 10 m/s?
A point on a standing wave that moves the most.
What is an antinode?
You push a slinky along its length and see regions of tight coils travel down it.
What kind of wave is this? (longitudinal)
Particles move parallel to the direction the wave travels. Compressions and rarefactions.
What is a longitudinal wave?
Cycles per second. Unit is the hertz.
What is frequency?
Sound travels at 340 m/s. A tone has a frequency of 440 Hz. What is the wavelength?
What is about 0.77 m?
Two crests meet and the resulting wave is taller.
What is constructive interference?
A coach tells a student to “follow through” when hitting a ball. In wave terms, longer contact time changes the impulse. What is the analogous idea when designing an egg-drop apparatus?
What is increasing the stopping time to reduce the peak force?
Particles at a water surface move in circles or ellipses.
What is a surface wave?
Time for one complete cycle.
What is the period?
A wave has a period of 0.25 s. What is its frequency?
What is 4 Hz?
A crest meets a trough and the resulting amplitude is smaller or zero.
What is destructive interference?
Two identical pulses meet on a spring. One is upright, one is inverted. What happens at the moment they overlap completely?
What is destructive interference (they cancel)?
Dominoes fall in a line. The dominoes mostly stay in place, but energy travels to the end.
What is an example of a wave (or mechanical wave)?
You measure the distance between two crests with a meter stick and time several cycles with a stopwatch.
How do you measure wavelength and period?
A rope is fixed at both ends and has a length of 1.5 m. It vibrates in two loops (second harmonic). What is the wavelength?
What is 1.5 m?
A wave appears not to travel. Nodes stay fixed. It is produced by two waves traveling in opposite directions.
What is a standing wave?
A fixed end reflects a pulse and flips it upside down. Why does this happen?
What is the medium at the fixed end cannot move, so the reflected wave inverts to satisfy the boundary condition?