Month: February 2019

The Physics of Car Crashes—and Why You Should Avoid Them

Two cars in crash test
“It’s not the fall that kills you; it’s the sudden stop at the end.”
― Douglas Adams

That quip by famed satirist and author of the 5-book “trilogy” The Hitchhiker’s Guide to the Galaxy may be moderately funny (all right, somewhat lame), but it also happens to be literally true. The scientific basis underlying this assertion can be expressed as a two-part logical equation, where…

  • “Vi” is your initial velocity
  • “t” is the total length of time of your fall
  • “a” is acceleration due to gravity as you fall
  • “Vf” is final velocity

…and where…

  • “m” is momentum
  • “ΔV” is change in velocity
  • “ΔT” is the time it takes to stop falling
  • “F” is force

Equation for falling and stopping

The first half of the equation denotes the fall (which is not fatal); the second half denotes the sudden stop (which most assuredly will be). Put another way, it’s not gravity you have to worry about, but Force.