# Warm-Up Exercise for lecture 19

## Due 8:00 am, Tues, Nov 4

Physics 105, Fall 2008

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

Gases change their volume when you apply pressure. Is the same true of solids?
☐ Yes, a substantial amount
☑ Yes, a small amount
☐ No

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

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

The gauge measures *differences* in pressures, not the real pressure values. To get the pressure inside the tire, you have to take the gauge pressure + atmospheric pressure. (Ralph's answer: no, the pressure inside is not really zero.)