# Do my homework?

1. Jan 26, 2004

### Krivanka

1) What is the mass of a column of air that has a cross-sectional area of 1

square centimeter and that extends from sea level to the top of the atmosphere?
What is the weight of this air column?
What is the pressure at the bottom of this column?

2) Is the value for atmosphere pressure at the surface of the earth constant?

Explain.

3)How does the pressure at the bottom of the 76-cm column of mercury in a

barometer compare with the pressure due to the weight of the atmosphere?

4)When you drink liquid through a straw, it is more accurate to say the liquid is

pushed up the straw rahter than sucked up the straw. What exactly does the

pushing? Explain.

5) Why will a vacuum pump not operate for a well that is deeper than 10.3m?

6)The atmosphere does not ordinarily crush cans. Yet it will crush a can after it

has been heated, capped, and cooled. Why?

7)Why can an aneroid barometer be used to measured altitude?

8)When air is compressed, what happens to its density?

9)a) How great is the buoyant force on a balloon that weighs 1 N when it is suspended by buoyancy in air?
b) what happens in the buoyant force decreases?
c) What happens if the uoyant force increases?

10) When the speed of a fluid flowing in a horizontal pipe increases, waht happens to the internal pressure in the fluid?

11)a)What are streamlines?
b)Is the pressure greater or less in regions where streamlines are crowded?

12)Does Bernoulli's principle provide a complete explanation for wing lift, or is there some other significant factor?

13)Why does a spinning ball curve in flight?

14)Small bubbles of air are released by a scuba diver deep in the water. As the bubbles rise, they become larger, smaller or stay about the same size? Explain.

15)It is easy to breathe when snorkeling with only your face beneath the surface of the water, but quite difficult to breathe when you are submerged nearly a meter, and nearly impossible when you are more than a meter deep(even if your snorkel tube reaches the surface). Figure out why, and explain carefully.

Thanks Much love

2. Jan 26, 2004