Archimedes Principle and Cannonballs
Most recent answer: 10/22/2007
- Anonymous
If the cannonball is heavier than water, then the amount of water the cannonball displaces when it sits on the bottom is less than that when it is responsible for when it is in the floating boat, and the total level in the lake will go down.
You can try it yourself with a plastic or styrofoam cup (the boat), some marbles, and a pot of water.
Tom
(published on 10/22/2007)
Follow-Up #1: What happens when the cannonball is fired?
- Jim Conlon (age 78)
southampton, ny USA
You interpret it quite correctly and for this reason the boat's level will elevate slightly so that the volume within the water decreases. The amount of the decreased underwater volume will be equal to the weight of the ball + gunpowder. However, the motion will be quite interesting: you obviously will have to fire the ball with a certain angle above the horizon (unless you want to destroy your own boat). The horizontal component will cause your boat to start travelling in the opposite way to . But the vertical component of the momentum should also be conserved, which means your boat needs to gain some speed downwards. It therefore will oscillate a bit up and down till the friction forces settle the elevation at this new equilibrium level.
Tunc
(published on 03/06/2015)