Exam 3 slides

The mass of a cubic meter of water is

1000 kg.

The weight of a 1-square-meter column of air that extends from sea level to the top of the atmosphere is

101,000N

What is the approximate mass of a 1-square-centimeter column of air that extends from sea level to the top of the atmosphere?

1kg

A scale from which a rock is suspended reads 5 N when the rock is out of water and 3 N when the rock is submerged. The density of the rock is

2.5x the density of the water

A weightless spring is stretched 10 cm by a suspended 1-kg block. If two such springs are used to suspend the block, one spring above the other, to effectively provide one double-length spring, then the total stretch of the double-length spring will be

20cm

It would be easier to pull evacuated Magdeburg hemispheres apart when they are

20km above the ocean

Room temperature on the Kelvin scale is about

300K

Doubling the thickness (diameter) of a rope will multiply its strength by

4

Tripling the linear size of an object multiplies its area by

9 and its volume by 27.

Which of the following is not a compound? A) air B) water C) ammonia D) salt E) All are compounds.

A) Air

Which of the following contracts most when the temperature is decreased? Equal volumes of A)helium. B) water. C) wood. D) iron. E) all contract the same.

A) helium

A block of styrofoam floats on water while a same size block of lead lies submerged in the water. The buoyant force is greatest on the A)styrofoam. B) lead. C) ...is the same for both.

B

Atmospheric molecules do not fly off into outer space because of A)their relatively low densities. B) Earth gravitation. C) cohesive forces. D) their relatively high speeds.

B) earth gravitation

A fish normally displaces its own A)weight of water. B) volume of water. C) both of these. D) neither of these.

C

Buoyant force is greatest on a submerged A) 1-cubic centimeter block of aluminum. B) 1-cubic centimeter block of lead. C) is the same on each.

C

As a helium-filled balloon rises in the air, it becomes A) more dense. B) heavier. C) bigger. D) all of these. E) none of these.

C) bigger

When an iron ring is heated, the hole becomes A) smaller. B) neither smaller nor larger. C) larger.

C) larger

Density

Mass of substance per unit volume. D=m/v

n the mountains, water in an open pot boils at

a lower temperature than at sea level

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

about 3/4 meter

Archimedes' principle for air

an object in the air is buoyed up with a force equal to the weight of displaced air

In a closed bottle are a certain number of hydrogen molecules. In an identical closed bottle at the same temperature and internal pressure are a certain number of nitrogen molecules. The bottle with the greater number of molecules is the one containing

both the same

Water pressure is greatest against the

bottom of a submerged object

In a vacuum, an object has no

buoyant force

When an object is partly or wholly immersed in a liquid, it is buoyed up

by a force equal to the weight of liquid displaced.

Surface tension of liquids

decreases as the liquid temperature increases

Which of these forces determines the chemical properties of an atom?

electrical force

When water at 4 degrees C is heated it expands. When water at 4 degrees C is cooled, it

expands

A floating ice cube contains small pieces of iron. During melting the water level will

fall

f object A in your left hand and object B in your right hand both have the same weight density, then they

have equal mass densities.

Some molecules are able to absorb large amounts of energy in the form of internal vibrations and rotations. Materials composed of such molecules have

high specific heats

When a volume of air is compressed, its temperature

increases

A bubble of air released from the bottom of a lake

it becomes larger as it rises

The effects of scaling are beneficial to swimmers who are relatively

large.

A heavy glass ball is placed in a pie pan that floats in a bucket. The water level at the side of the bucket is marked. Then the glass ball is removed and allowed to sink in the bucket. The water line at the side of the bucket is now

lower

If the specific heat of water were lower than it is, ponds in the cold of winter would be

more likely to freeze

Increase the pressure in a container of oxygen gas while keeping the temperature constant and you increase the

neither the molecular kinetic energy or the molecular speed.

Increased air pressure on the surface of hot water tends to

prevent boiling

A refrigerator

removes internal energy from inside the refrigerator.

Assuming all the atoms exhaled by Julius Caesar in his last dying breath are still in the atmosphere, then we probably breathe one of those atoms with each

single breath

The energy source responsible for the motion of molecules that make up the atmosphere is

solar power

Firefighters find that the temperature of burning material is best lowered when water is

sprayed in a fine mist

If molecules in a gas sample moved so they completely missed each other, the gas's temperature would

stay the same

Which will bounce higher off a hard surface? A)a steel ball B)a rubber ball C) Both bounce the same.

steel ball

hooke's law

the amount of stretch or compression of an elastic material is directly proportional to the applied force. F=k (spring constant) x change in x

Atmospheric pressure:

the pressure exerted against bodies immersed in the atmosphere. it results from the weight of air pressing down from above. At sea level, atmospheric pressure is about 101 kPa

Bernoulli's principle

the pressure in a fluid moving steadily without friction or outside energy input decreases when fluid velocity increases.

Boyle's law

the products of pressure and volume is constant for a given mass of confined gas, as long as temperature remains unchanged. P1P1=P2V2

Newtons's law of cooling:

the rate of loss of heat from an object is proportional to the temperature difference between the object and its surroundings.

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

the same height as in the larger tube.

scaling

the study of how size affects the relationships among weight, strength and surface.

conduction:

the transfer of heat energy by molecular and electron collisions within a substance (especially a solid)

convection:

the transfer of heat energy in gas or liquid by means of currents in the heated fluid. the fluid moves, carrying energy with it.

weight density

the weight of a substance divided by its volume WD=w/v

Atmospheric pressure is caused by the

weight of the atmosphere