# Warm-Up Exercise for lecture 18

## Due 8:00 am, Thurs, 29 Oct 2009

Physics 105, Fall 2009

Enter your 3-digit class identification number:

Enter the last 4 digits of your BYU ID:

Did you complete the reading assignment? (Typically this means at least 20-30 minutes looking over the assigned sections of the book.)
☐ yes ☐ no

Where is the pressure greater, one meter beneath the surface of Lake Michigan or one meter beneath the surface of a swimming pool?
☐ Lake Michigan
☐ swimming pool
☐ the same

The buoyant force of a submerged object always equals:
☐ the weight of the object
☐ the net force on the object
☐ the weight of the water that would otherwise occupy the object's space

(Caution: this one requires some careful thinking.) A cannon sits in a boat on a lake. A person now throws the cannon overboard and it sinks to the bottom. Compared to when the cannon was in the boat, will the overall water level of the lake (as measured on the shore) rise, fall or stay the same?
☐ rise
☐ fall
☐ stay the same

Ralph measures the pressure in his flat tire with a standard automotive pressure gauge. The gauge reads zero. Should Ralph really believe that the pressure inside the tire is zero, or should he not? Explain.

The comments in the next next two boxes go into a big, mostly anonymous text file that I skim through before the morning lecture, using the comments to help me plan class discussion. ("Mostly anonymous", because I can track down who made what comment, but it takes some effort on my part to do so.) Therefore, if you really want to make sure I see your question/comment and answer it individually, you should send it to me via email and not through this form.

Which part of today's assignment was particularly hard or confusing? What would you like to spend extra time on in class?