# Week 17

**Reading:**Chap 15, fluids

**Topics:**Archimedes' principle; Hydrostatic pressure; Pascal's principle; Bernoulli's law

**Lab:**Buoyancy and archimedes' principle.

**Homework Problems: Due on Monday, Dec. 11 at noon.**

- I
**ce cube:**A large ice cube, whose density is 0.917 g/cc, is placed in a glass. Water is then poured into the glass until the glass is full to the rim.

- First, what fraction of the ice cube is submerged? (Solution: 91.7 percent)
- When the ice melts, will the water level overflow the glass, will it fall below the rim, or will it remain the same? Explain your answer. (Solution: it would remain at the same level. Suppose the ice cube had a volume of 1 cc. 0.917 cc was below water. When it melts, the new volume will be 0.917 cc, since its density increased by just this much.)

**Hydraulics:**A fluid-filled syringe has a plunger with a diameter of 1 cm. The needle has a diameter of 1 mm. The plunger is depressed at a rate of 1 cm per second.

- With what speed will the fluid squirt from the tip of the needle? (Since the cross-sectional area of the needle is 1/100 that of the plunger, the speed will be 100 times as great. So the fluid squirts out at 100 cm/second.)
- If the end of the needle is capped, and a force of 1 pound is applied to the plunger, what force will be applied to the end cap? Explain your answer. (By pascal's principle, the force will be 1/100 of a pound)

**Quiz: Next week covering fluid statics and dynamics**

**Gallery of Fluid Motion**