Sink or Float?
Some objects sink and some float. Can you design one that does both, like a submarine?
What you will need:
- One or more plastic film canisters* for your “submarine(s)”
*You may get empty film canisters from many local photofinishing locations that process film, and if you have a choice, the clear-whitish ones let you see what’s going on inside!
- 2 liter soda bottle with the top third cut off to hold your “ocean”
- Several Alka-Seltzer® type of fizzy tablets
- Handful of pennies
Here’s what to do:
Carefully, make a small hole on the lid of the film canister with the pointy ends of a pair of scissors. (Adults help younger kids). Fill up your ocean two-thirds of the way with water and you’re ready to go diving!
Take it further:
- How can you make your submarine sink to the bottom of the ocean?
- What is the fewest number of pennies you can add to get it barely sink?
- What happens when you now add a piece of a fizzy tablet to your submarine and close the lid? It may splash a bit!
- Does the amount of water or fizzy tablet make a difference in the action of your submarine?
- How can you get your submarine to sink, and then slowly rise to the surface two, five, or ten seconds later?
- Does it matter how your submarine lies on the ocean floor for it to be able to float back up?
- Does the size of the hole have an impact on the way the submarines behave?