Physical Science
Chapter 3 review questions
Questions page 75.
1. When the water inside the dropper rises the dropper starts sinking. When the water inside
the dropper lowers the dropper rises.
2. The denser the dropper is (the more water is has in it) the lower it is in the water.
3. A submarine can control the amount of water to control their densities to go up or down
in the water.
Three familiar states of matter: solid, liquid and gas (p 78)
Section 1 Review page 81
1. List three main points of the kinetic theory of matter.
1. Atoms and molecules are always in motion
2. Particles move faster at high temperatures than they do at low temperatures.
3. At any temperature heavier particles move slower than lighter particles do.
2. State two examples for each of the four states of matter.
Solid: marbles and brass metal or coins
Liquids: water, orange juice, milk, mercury
Gas: oxygen, nitrogen, helium
Plasma: fire and lightening
3. Compare the shape of and volume of solids, liquids, and gases.
Solids: have definite volume and shape
Liquids: have definite volume but no definite shape
Gases: have neither definite volume nor definite shape
4. Describe the relationship between temperature and kinetic energy.
Temperature is a direct measure of average kinetic energy.
5. Compare the temperature and thermal energy of hot soup in a small mug and that of
hot soup in a large bowl.
Both would have the same temperature, but the large bowl of soup has more thermal energy
than the small mug because there is more matter present in the bowl.
6. Which particles have the strongest attraction between them: the particles of a gas, the
particles of a liquid, or the particles of a solid?
Particles of a solid have a stronger attraction to one another
7. Use the kinetic theory to explain how a dog could find you by your scent.
The gas particles move freely in all directions. Therefore a dog could get your scent if you
touch something or walked on the ground, it could pick up your scent.
Section 2 Review page 88
1. Describe the following changes of state, and explain how particles behave in each state.
a. Freezing: it goes from a liquid to a solid and the particles slow down
b. Boiling: it goes from a liquid to a gas and the particles speed up
c. Sublimation: it goes from a solid to a gas and the particles speed up
d. Melting: it goes from a solid to a liquid and the particles speed up
2. State whether energy is released or whether energy is required for the following
changes of state to take place
a. Melting: energy is required
b. Evaporation: energy is required
1
Physical Science
Chapter 3 review questions
c. Sublimation: energy is required
d. Condensation: energy is being released
3. Describe the role of energy when ice melts and when water vapor condenses to form
liquid water.
As energy is transferred to ice, the attraction between water molecules is broken and the ice
melts. As water vapor releases energy, the attraction between molecules increases and liquid
water condenses.
4. State the law of conservation of mass and the law of conservation of energy, and explain
how they apply to changes of state.
Law of conservation of mass: Mass can not be created or destroyed
Law of conservation of energy: Energy can not be created or destroyed
During a change of state the total mass and total energy remain constant.
5. If you used dry ice in your holiday punch, would it become watery after an hour? Why
or why not?
No, because dry ice is solid carbon dioxide. It undergoes sublimation and therefore turns
directly from a solid into a gas.
Section 3 Review page 94
1. Explain how differences in fluid pressure create buoyant force on an object.
Fluid pressure is exerted on all sides of an object. The horizontal pressures cancel each other
out. The pressure exerted at the bottom is greater than the pressure exerted at the top, and it
creates a buoyant forces known as lift (buoyancy).
2. State Archimedes’ principle, and give an example of how you could determine a
buoyant force.
Archimedes’ principle states that the buoyant force in a fluid equals the weight of the fluid
the object displaces. We could weigh the fluid that was displaced.
3. State Pascal’s principle. Give an example of its use.
Pascal’s principle states that pressure applied to a fluid in a closed container is transmitted
equally throughout the fluid. Hydraulic lifts and hydraulic jacks would be two examples.
4. Compare the viscosity of milk and the viscosity of molasses.
The viscosity of molasses is greater than that of milk
5. An object weighs 20 N. It displaces a volume of water that weighs 15 N.
a. What is the buoyant force on the object? The buoyant force will be 15 N
b. Will the object float or sink? Explain. It will sink because its weight exceeds its
buoyant force.
6. Iron has a density of 7.9 g/cm3. Mercury has a density of 13.6 g/cm3. Will iron float or
sink in mercury. Explain. It will float because its density is less than that of mercury.
7. Two boats in a flowing river are sailing side-by-side with only a narrow space between
them.
a. What happens to the fluid speed and the pressure between the two boats?
The fluid speed increases because the fluid pressure decreases.
b. How could the changes in fluid speed and pressure lead to a collision of the
boats? As the fluid speed between the boats increases the fluid pressure
decreases, so if this happens the boats would be pushed together.
8. A water bed that has an area of 3.75 m2 weighs 1,025 N. Find the pressure that the
water bed exerts on the floor.
2
Physical Science
Chapter 3 review questions
1,025 N divide by 3.75 m2 equals 273 Pascals
9. The small piston of a hydraulic lift has an area of 0.020 m2. A car weighing 12,000 N is
mounted on the large piston (area = 0.90 m2). What force must be applied to the small
piston to support the car?
12,000 N divide by 0.90 m2 times 0.020 m2 equals 270 N
Section 4 Review page 101
1. List four properties of gas.
Gases will flow, they have low densities, they are compressible, and they expand to fill their
containers.
2. Explain why the volume of a gas can change.
The attraction between gas particles is not very strong so the volume of a gas can easily
change.
3. Describe how gases are different from solids and liquids, and give examples.
Unlike solids and liquids gases have very low densities and can easily change volume.
An example: filling tires, filling balloons, filling scuba tanks
4. Identify what causes the pressure exerted by gas molecules on their container.
By the gas particles colliding with the walls of their container.
5. Restate Boyle’s law, Charles’s law, and Gay-Lussac’s law in your own words.
a. Boyle’s Law: the volume of a gas increases as pressure decreases (at a constant
temperature)
b. Charles’s Law: the volume of gas increases as the temperature increases
c. Gay-Lussac’s Law: gas pressure increases as temperature increases at a constant
volume.
6. Identify a real-life example for each of the three gas laws.
a. Boyle’s Law: let the air out of a tire, the air expands outside of the tire, as the
pressure on the air decreases
b. Charles’s Law: when a balloon is exposed to heat it will expand.
c. Gay-Lussac’s Law: if you heat a spray can it may explode due to an increase in
pressure.
7. Why do gases have low densities?
Their particles are very far apart.
8. When scientists record the volume of a gas, why do they also record the temperature
and the pressure?
The volume of a gas can be changed by changing either the temperature or the pressure.
9. Predict what would happen to the volume of a balloon left on a sunny window-sill.
Which gas law predicts this result?
It would cause the temperature on the inside of the balloon to increase. Charles’s law, the
volume will increase as the temperature increases.
10. A partially inflated weather balloon has a volume of 1.56 x 103 L and pressure of 98.9 kPa.
What is the volume of the balloon when the balloon is released to a height where the pressure
is 44.1 kPa?
Take (1.56 x 103 L) times 98.0 kPa over 44.1 kPa. Equals 3.50 x 103 L
3
Physical Science
Chapter 3 review questions
END OF CHAPTER QUESTIONS page 106-107
1. Make a comparison table to compare the five changes of state that are described in this
chapter.
Melting
Freezing
Evaporation
Condensation
Sublimation
2. Describe four states of matter by using the terms solid, liquid, gas, and plasma. Describe
the behavior of particles in each state.
Solid: the particles are held closely together and they vibrate
Liquid: the particles are close together but they slide past one another
Gas: the particles are spread apart and they fill the available space
Plasma: the particles spread apart to fill spaces and they are broken apart
3. Describe how pressure is exerted by fluids.
Fluids exert pressure evenly in all directions.
4. Describe the buoyant force, and explain how it relates to Archimedes’ principle.
Buoyant force is the upward force exerted on an object floating on a fluid. Archimedes’
principle states that the buoyant force is equal to the weight of the volume of the fluid that is
displaced by the object.
5. Which of the following assumptions is not part of the kinetic theory?
6. Three common states of matter are
7. During which of the following changes of state do atoms or molecules become more
ordered? B. condensation
8. Which of the following describes what happens as the temperature of a gas in a balloon
increases?
9. Fluid pressure is always directed
10. Matter that flows to fit its container includes
11. If an object that weighs 50 N displaces a volume of water that weighs 10 N, what is the
buoyant force on the object?
12. State the law of conservation of energy and the law of conservation of mass. Explain what
happens to energy and mass in a change of state.
13. For each pair, explain the difference in meaning
a. solid and liquid: A solid has definite shape and volume. A liquid the substance
takes the shape of its container, but has definite volume.
b. Boyle’s law and Charles’s law: Boyle’s law states that when the pressure of a gas
increases its volume decreases. Charles’s law states that when the temperature of
a gas increases its volume also increases.
c. Gay-Lussac’s law and Pascal’s principle: Gay-Lussac’s law states that when the
temperature of a gas increases its pressure also increases. Pascal’s principle states
that when the pressure is applied to a fluid in a closed container it is transmitted
equally throughout the fluid.
14. Using the graph: What type of relationship does the graph represent: direct or inverse?
15. To which law or principle does the graph apply?
4
Physical Science
Chapter 3 review questions
16. Explain what happens to the pressure of a gas if the volume of the gas is tripled.
Assume that the temperature remains constant.
Boyle’s law states that the volume of a gas in inversely proportional to its pressure. So if the
volume is tripled the pressure would drop to 1/3.
17. Why are liquids instead of gases used in hydraulic brakes?
Liquids are used instead of gases because they can not be compressed easily. Gases are easily
compressed.
18. After taking a shower, you notice that the mirror is foggy and covered with very small
droplets of water. Explain how this happens by describing where the water comes from
and the changes the water goes through.
As you take a shower, some of the liquid water evaporates and becomes a gas. When the gas
touches the mirror, it releases some of its energy during condensation, which changes it into
droplets on the mirror.
19. An iceberg is partially submerged in the ocean. At what part of the iceberg is the water
pressure the greatest?
At the lowest depth.
20. Use Boyle’s Law to explain why bubbled packing wrap pops when you squeeze it.
As the bubble is squeezed to a smaller volume, the pressure inside the bubble increases until
it bursts the bubble.
21. Will a ship loaded with plastic-foam balls float higher or lower in the water than an
empty ship? Explain.
The ship will float lower in the water, because the plastic foam balls add to the ships total
mass, but do increase its volume. The overall density of the ship is increased which causes it
sink a little.
22. All vacuum cleaners have a high-speed fan. Explain how this fan allows the vacuum
cleaner to pick up dirt.
The fan causes the air inside the vacuum to move faster, which will decrease its pressure.
(The higher air pressure outside the vacuum then pushes dirt into the vacuum cleaner.)
GRAPHING SKILLS
23. Kate place 100 mL of water in each of five different pans. She then placed the pans on a
windowsill for a week and measured how much water evaporated. Graph her data,
which are shown in the table. Surface area is on the x-axis
a. Is the graph linear or nonlinear? linear
b. What does this answer tell you? A linear line indicates that an increase in surface
area caused an increase in evaporation.
24. The graph shows effects of heating on ethylene glycol, the liquid commonly used as
antifreeze. Before the temperature is 197 degrees C., the temperatures increasing or
decreasing? The temperature is increasing. What physical change is taking place when
the ethylene glycol is at 197 degrees C. Ethylene changes state from a liquid to a gas
(boiling). Describe what is happening to the ethylene glycol molecules at 197 degrees C.
At 197 degrees they are absorbing energy to vaporize. How do you know this is
happening? There is no increase in temperature.
25. 1500 N divided by 500 Pa = 3 m2
500 Pa divided by 2 = 6 m2
6
2
2
26. (1.0 x 10 N) (0.7m )divided by 140 m equals 5 x 105 N
27. (1.8 kPa x 2.8 L)/ 1.2 kPa equals 4.2 L
28. (650 kPa * 2.2 L)/ 115 L = 12 L
5