chapter14

Question 1

Atmospheric pressure decreases with increasing _________.

Answer 1

altitude

Question 2

What is the mass of a cubic meter of air at room temperature (20°C)?

Answer 2

1.21 kg

Question 3

How does the pressure at the bottom of a 76-cm column of mercury in a barometer compare with the air pressure at the bottom of the atmosphere?

Answer 3

the pressures are equal

Question 4

How does the weight of mercury in a barometer compare with the weight of an equal cross-section of air from sea level to the top of the atmosphere?

Answer 4

they are equal

Question 5

Why would a water barometer have to be 13.6 times taller than a mercury barometer?

Answer 5

Mercury is 13.6 times denser than water

Question 6

When you drink liquid through a straw, is it more accurate to say the liquid is pushed up the straw rather than sucked up the straw? What exactly does the pushing?

Answer 6

The atmospheric pressure outside the straw pushes the liquid toward the lower pressure in your mouth

Question 7

Why won’t a vacuum pump operate for a well that is deeper than 10.3 m?

Answer 7

Atmospheric pressure equals the pressure under 10.3 m of water and so can push water no higher

Question 8

By how much does the density of air increase when it is compressed to half its volume?

Answer 8

It doubles.

Question 9

What happens to the air pressure inside a balloon when it is squeezed to half its volume at constant temperature?

Answer 9

doubles

Question 10

Does the air exert a buoyant force on all objects in air or only on objects such as balloons that are very light for their size?

Answer 10

Air exerts a buoyant force on all objects.

Question 11

Why are high-altitude research balloons only partially inflated when launched?

Answer 11

The atmospheric pressure decreases as they rise, so they expand. If they were fully inflated at launch, they would burst at high altitudes

Question 12

A helium-filled balloon will reach its maximum altitude when __________.

Answer 12

its weight equals the weight of displaced air

Question 13

What happens to the internal pressure in a fluid flowing in a horizontal pipe when its speed increases?

Answer 13

The pressure decreases when the speed increases.

Question 14

What happens to the internal pressure in a fluid flowing in a horizontal pipe when its speed decreases?

Answer 14

The pressure increases when the speed decreases

Question 15

Is the fluid that goes up the inside tube in a hand sprayer pushed up the tube or sucked up the tube? Explain.

Answer 15

It is pushed up the tube by atmospheric pressure into the low-pressure, fast air stream.

Question 16

The air in your classroom has

Answer 16

• mass
• weight
• energy

Question 17

In drinking soda or water through a straw, we make use of

Answer 17

atmospheric pressure

Question 18

At normal atmospheric pressure and temperature, 1 cubic meter of air has a mass of about

Answer 18

1.25 kg

Question 19

When a suction cup sticks to a wall it is

Answer 19

pushed to the wall by the atmosphere

Question 20

The weight of air in a column 1-m2 in cross section that extends from sea level to the top of the atmosphere is

Answer 20

101,000 N

Question 21

A column that extends from sea level to the top of the atmosphere contains a certain mass of air. If the column instead contained the same mass of mercury, its height would be about

Answer 21

3/4 meter

Question 22

Consider two mercury barometers, one with twice the cross-sectional area of the other. Neglecting capillarity, compared with the wider tube, mercury in the smaller tube will rise

Answer 22

to the same height

Question 23

It would be easier to pull the evacuated Magdeburg hemispheres apart if they were

Answer 23

20 km above the ocean surface.

Question 24

The weight of air in a bathtub (about 1/3 cubic meter) is about the same as the weight of

Answer 24

pound of butter

Question 25

When a gas in a container is squeezed to half its volume with no change in temperature, the gas pressure

Answer 25

doubles

Question 26

When boarding an airplane you bring a bag of chips. While in flight the bag puffs up, because

Answer 26

air pressure in the air-tight bag is greater than cabin air pressure

Question 27

A bubble of air released from the bottom of a lake

Answer 27

becomes larger as it rises

Question 28

The buoyant force of the atmosphere on a body is equal to the

Answer 28

weight of air displaced

Question 29

Archimedes' principle applies to

Answer 29

- fluid - gas - liquid

Question 30

The buoyant force on a one-ton blimp hovering in air is

Answer 30

one ton

Question 31

As a high-altitude balloon sinks lower into the atmosphere, it undergoes a decrease in

Answer 31

volume

Question 32

A helium-filled balloon released in the atmosphere will rise until

Answer 32

the balloon and surrounding air have equal densities.

Question 33

Compared with the buoyant force of the atmosphere on a 1-liter helium-filled balloon, the buoyant force of the atmosphere on a nearby 1-liter solid iron block is

Answer 33

same

Question 34

Compared to the buoyant force of the atmosphere on a 1-kilogram iron block, the buoyant force on a nearby 1-kilogram helium-filled balloon is

Answer 34

considerably more

Question 35

If you stand on a weighing scale and suddenly the atmosphere vanishes, taking buoyancy into account, the scale reading

Answer 35

increases

Question 36

Airplane flight best illustrates

Answer 36

Bernoulli's principle.

Question 37

An umbrella tends to move upwards on a windy day principally because

Answer 37

air pressure is reduced over the curved top surface

Question 38

When a gas in a container is squeezed to half its volume, its density

Answer 38

doubles

Question 39

As a balloon rises higher and higher into the atmosphere its

Answer 39

none

Question 40

As a high-altitude balloon rises higher into the atmosphere, it undergoes a decrease in

Answer 40

density

Question 41

An object in a vacuum has no

Answer 41

buoyant force

Question 42

A common 5-liter metal can will float in air if it is

Answer 42

no way, unless the displaced air weighs more than the can and its contents

Question 43

An empty jar is pushed open-side downward into water so that trapped air cannot escape. As it is pushed deeper, the buoyant force on the jar

Answer 43

decreases

Question 44

A spinning tossed baseball veers off course in the direction of

Answer 44

reduced air pressure on the ball.

Question 45

When you blow air between a pair of closely-spaced Ping-Pong balls suspended by strings, the balls will swing

Answer 45

toward each other

Question 46

As a balloon high in the atmosphere descends, it undergoes a decrease in

Answer 46

volume

Question 47

A large block of wood and a smaller block of iron on weighing scales both register 1 ton. Taking buoyancy of air into account, which has the greater mass?

Answer 47

wood

Question 48

How does the mass of the air in your bedroom compare to your mass?

Answer 48

they are approximately equal