Beata's lab sheet shows a snapshot of a slinky wave: dots for coils, bunched in some stretches, spread in others. Three jobs this time: mark the compressions, mark the rarefactions, and bracket one wavelength.
No crests or troughs here; the landmarks are spacing regions. The routine reads the spacing, then brackets the repeat.
Read the spacing first. Find the stretches where the dots sit squeezed together: the compressions.
Find the stretches where the dots sit spread apart: the rarefactions.
Check the alternation: compression, rarefaction, compression, along the whole snapshot.
Bracket one wavelength between two successive identical points: the middle of one compression to the middle of the next compression.
Rarefaction to next rarefaction also works: the same repeat distance at the other landmark.
A compression to the very next rarefaction is only half a wavelength: those regions are not identical.
Label a snapshot of a long spring wave: dots bunch at three evenly spaced stretches, with wide stretches between. Walk the moves.
The three bunched stretches are compressions.
The wide stretches between them are rarefactions.
The wavelength bracket runs from the middle of one compression to the middle of the next.
The snapshot carries compression and rarefaction labels and one wavelength bracket, compression to next compression.
Anselm brackets from the middle of one rarefaction to the middle of the next rarefaction and labels it one wavelength. Does his bracket need redrawing?
A wavelength bracket needs two successive identical regions.
Two successive rarefactions are identical regions.
No. Rarefaction to next rarefaction spans one wavelength, so his bracket stands.
A snapshot of a coiled cord marks three regions: J with tightly bunched coils, K with widely spread coils, and L with evenly spaced coils. Which letter belongs under the label compression?
Three brackets are drawn on a spring-wave snapshot: J from the middle of one bunched stretch to the middle of the next bunched stretch, K from the middle of a bunched stretch to the middle of the very next spread stretch, and L across one bunched stretch only. Which bracket spans one wavelength?
Cosmo brackets from the middle of one spread-out stretch to the middle of the next spread-out stretch on a spring snapshot and labels it one wavelength. Is his label correct?
A snapshot of a long spring marks four regions: M with bunched coils, N with evenly spaced coils, P with widely spread coils, and Q with bunched coils again. Which letter belongs under the label rarefaction?
On a longitudinal snapshot, which bracket spans one wavelength?
The snapshot shows dense coil stretches centered at the marks J, L, and N, with spread stretches between them. How many complete wavelengths sit between J and N?