All mysteries
Mystery #2Tier 2momentum recoil physics

Why does a cannon lurch backwards the moment it fires a ball forwards?

A cannon fires, and the heavy iron ball roars off across the field. But in the very same instant the enormous cannon jerks backwards on its wheels, hard enough to roll away. Nobody pushed it from the front. So why does firing something forwards throw the cannon back the other way?

A historic cannon being fired at a fort, with a burst of flame and a cloud of white smoke leaving the muzzle.
Photo: Pahcal123 · CC BY-SA 4.0 · via Wikimedia Commons

Your guess

Why do you think the cannon leaps backwards just as the ball leaves it?

There's no single magic word to type, have a go in your own words, then reveal the answer to see how close you got.

Make a guess to unlock the hints and the answer.