More Tinkering

Chapter 20 Floating and Sinking

Play with stuff in water to get a feel for Archimedes’s law.

Here’s a classic physics question we ask high school teachers in Timor. It involves a big rock in a boat that is floating on a small pond. A post stuck in the bottom of the pond extends up above the surface of the water, and the level of the pond can be seen on the post. The pilot of the boat picks up the rock and chucks it out of the boat into the pond. After the waves calm down, the pilot peeks at the post to check the level of water in the pond. What does she find?

• The water line went down, meaning the pond level decreased.
• The water line went ...