Noll's family car idles at a stoplight, and the right rear door panel buzzes loudly. A little faster or slower, and the buzz vanishes.
Something in this scene is resonating, and something is driving it. Naming which is which is this lesson's skill: two reads, every time.
Ask first: which thing is doing the big, built-up vibrating? Here it is the door panel. The panel is the resonating system.
Ask second: which thing supplies the repeated driving vibrations? Here it is the engine. The engine is the driver.
At other engine speeds the panel is still driven, but with no match there is no build-up: just a small forced vibration nobody notices.
The driver is rarely the loud thing. The engine hums along unchanged; the panel is what swings large.
In a band room, one cymbal on its stand hums loudly whenever the electric bass holds one particular note. Name the resonating system and the driver.
The cymbal is the thing whose vibration builds up large.
The bass note supplies the repeated driving vibrations, and only its one matching note sets the cymbal off.
The cymbal is the resonating system, and the bass note is the driver.
A gym's ceiling light fixture rattles only when the big air blower runs on its low setting. Name the resonating system and the driver.
The fixture is the thing whose vibration builds up large.
The blower supplies the repeated driving vibrations, and only its low setting matches the fixture's natural frequency.
The light fixture is the resonating system, and the blower is the driver.
A pickup truck idles, and its loose license plate buzzes loudly at that one idle speed. Which thing is resonating?
A bathroom mirror hums only while the building's water pump runs. Which thing is the driver?
Ottoline says: 'If a car door buzzes only at one engine speed, the door panel is resonating and the engine is driving it.' Is Ottoline correct?
At a stadium, one section of metal bleachers sways alarmingly only when the crowd stomps at one particular rate. Which statement is correct?
In a basement, a ceiling pipe clanks loudly only while a dryer's drum passes one particular speed. Which statement is correct?
A van's dashboard rattles loudly only at 50 mph, where the engine turns at one particular rate. What does the only-at-50-mph clue tell you?