Workout: Buoyancy

Read

Read the web pages: Pressure and Buoyancy.

Launch

To give you some practice on working with forces arise from fluid pressure, go to the PhET simulation Density and Buoyancy to perform a few tasks.

Set up

You can start with the screen as it comes up. Your screen should look like the image below.

Answer these questions

1. Choose "Same mass" for the blocks. Use the scale to determine how much each block weighs. (Hint: Since they have the same mass they will weigh the same.) Yet one block floats and the other sinks. Why? 
2. Weigh the block that sinks under water. Is the effect of the water around it to push it up or down? Why does it do this? 
3. You are given the mass of the block that sinks and can measure what it weighs on a scale outside of the water and under the water. Is that enough information to find the volume of the block? If so, explain how you would get it. (Don't do it.) If not, what other information would you need? 
4. Now consider the block that floats. How much water does it displace? From that information and the weight of the block, can you infer the volume of the block? If so, explain how you would get it. (Don't do it.) If not, what other information would you need? 

Joe Redish, Fall 2016