Question 1

Which of the following best explains why atmospheric pressure decreases with altitude?

Accepted Answer

There is less air above a given surface as altitude increases, so the weight of the air (and thus the pressure) is less.

Question 2

A barometer using mercury shows a column height of 760 mm at sea level. If water (density $$1000\ \mathrm{kg/m^3$}) $$were used instead of mercury (density $$13,600\ \mathrm{kg/m^3$}$$), what would be the approximate height of the water column at sea level?

Accepted Answer

$$10.3\ \mathrm{m}$$

Question 3

According to Boyle's Law, if the volume of a gas is decreased from $$6.0\ \mathrm{L} to$$ $$2.0\ \mathrm{L} at $$constant temperature, what happens to the pressure?

Accepted Answer

It triples.

Question 4

A weather forecaster uses a barometer to predict a storm. What change in atmospheric pressure would most likely indicate an approaching storm?

Accepted Answer

A rapid decrease in atmospheric pressure.

Question 5

A hot air balloon rises because:

Accepted Answer

The weight of the air displaced is greater than the weight of the balloon.

Question 6

A piston compresses a gas from $$4.0\ \mathrm{L} to$$ $$1.0\ \mathrm{L} at $$constant temperature. If the initial pressure was $$100\ \mathrm{kPa}$$, what is the final pressure?

Accepted Answer

$$400\ \mathrm{kPa}$$

Question 7

Which of the following is a real-world application of Bernoulli's Principle?

Accepted Answer

A perfume atomizer sprays liquid when air is blown across the tube opening.

Question 8

Why can a stream of water from a fire hose knock a person off their feet, even though the pressure within the fast-moving water is reduced?

Accepted Answer

The force is due to the change in the water's momentum when it hits the person.

Question 9

Which of the following best describes plasma?

Accepted Answer

A gas in which atoms are ionized, with free electrons and ions.

Question 10

A dirigible hovers in air. What does it displace?

Accepted Answer

Both its volume and its weight of air.

Question 11

If the atmospheric pressure at sea level is $$101\ \mathrm{kPa}$$, what is the force exerted by the atmosphere on a $$2.0\ \mathrm{m}^2$$ surface?

Accepted Answer

$$202,000\ \mathrm{N}$$

Question 12

Why is mercury used in barometers instead of water?

Accepted Answer

A water barometer would be impractically tall due to water's lower density.

Question 13

A balloon filled with helium rises until:

Accepted Answer

The weight of the displaced air equals the total weight of the balloon.

Question 14

According to Bernoulli's Principle, what happens to the pressure in a fluid as its speed increases?

Accepted Answer

The pressure decreases.

Question 15

Which of the following is NOT a property of plasma?

Accepted Answer

It cannot conduct electricity.

Question 16

A piston in an airtight cylinder is withdrawn so that the volume of the air chamber increases by a factor of 4. What happens to the pressure?

Accepted Answer

It decreases by a factor of 4.

Question 17

Which of the following is a consequence of Bernoulli's Principle in architecture?

Accepted Answer

Wind blowing over a peaked roof can lift the roof off a house.

Question 18

Why can't you drink water through a straw more than $$10.3\ \mathrm{m}$$ high at sea level?

Accepted Answer

Atmospheric pressure can only support a column of water up to $$10.3\ \mathrm{m}.$$

Question 19

Which of the following is an example of plasma in everyday life?

Accepted Answer

A fluorescent lamp when turned on.

Chapter 14: Gases – Physics Study Notes

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