Topic
Waves
8 articles
Physics
Why does a whip crack?
A person swings their arm at walking pace and something at the far end of a leather rope breaks the sound barrier. Nothing is exploding and nothing is hitting anything. The bang is a small piece of air being shoved out of the way faster than it can move.
Technology
Why did the Millennium Bridge wobble?
A brand new footbridge opened across the Thames, swayed alarmingly under the crowd, and shut two days later for two years. Nothing was broken and nothing was undersized. The people crossing it were the missing part of the design.
Technology
Why does wifi go through walls but light doesn’t?
Both are the same kind of wave, traveling at the same speed, made of the same stuff. One crosses a brick wall without noticing it and the other cannot get through a sheet of paper. The difference is size.
Physics
Why does helium make your voice squeaky?
Everybody says the gas puts your voice up high. Record it and measure it, and the note you are singing has hardly moved at all. Something else about you got smaller, and it was not your voice.
Physics
Why can you hear around a corner but not see around one?
A voice from the kitchen reaches you in the hall, around the corner, without any trouble at all. Light from that same kitchen stops dead at the door frame.
Physics
How do noise-canceling headphones erase a sound?
Press one button on a plane and the engine roar drops away, while the passenger beside you stays perfectly clear. Nothing was plugged, and nothing was switched off.
Physics
Why does thunder rumble on and on instead of going bang?
The flash is over in a heartbeat, but the noise behind it can roll for a dozen seconds. Something is stretching one very short bang into something very long.
Biology
Why does your own voice sound wrong on a recording?
Someone plays back a video from the school concert. Every other voice on it is exactly right. Yours belongs to a stranger, and the whole room insists the stranger is you.