Short · Physics
Why does a whip crack?
A whip crack is a tiny sonic boom. Your hand sends a loop rolling down the whip, and the whip gets thinner and thinner, so the same energy is carried by less and less mass and the loop speeds up. With a tip one tenth as thick as the handle, the loop ends up about 30× faster, past the speed of sound. Neal Stephenson has written five essays about giant steel whips: not to orbit, he says, but even a head start saves rocket fuel.
Opens Whip Crack Lab. Change the same thing yourself.
Transcript
Neal Stephenson has written five essays about this sound. A whip crack is a tiny sonic boom. Your hand sends a loop rolling down the whip. The whip gets thinner and thinner, so the same energy is carried by less and less mass, and the loop speeds up. Now thin the tip. At one tenth the thickness, the loop ends up thirty times faster, past the speed of sound. Could a giant steel whip launch a rocket? Stephenson says not to orbit, but even a head start saves fuel. Thin the tip yourself at Explainer Tools dot com.
Learn more
More ways to space
Stephenson’s steel whips are one of four launch ideas he talked through on Core Memory. The guide compares all four, and the other three films are here.
- Topic guideWhat are the ways to space besides a rocket from the ground?Towers, slings, space guns and whips: what each buys, what each costs, and why rockets won.
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Short · 36 secondsHow does SpinLaunch throw rockets into space?SpinLaunch throws its rockets: double the speed and the force quadruples, to about 10,000 g.
Short · 39 secondsWhy build a 10 km space gun?Longshot’s 10 km gun spreads the push out: a few hundred g for satellites, never for people.