SCI 8: Fluids
NAME: _______ANSWERS________ HOMEROOM: _____
Fluids Unit Review
1. Make a list of five fluids that can be found in each of these places.
a. The human body – blood, saliva, urine, stomach acid
b. A kitchen – maple syrup, dish soap, vegetable oil, oven cleaner
c. A Garage – motor oil, windshield washing fluid, gasoline, window cleaner
2. Make a list of ten machines or devices that use fluid power systems.
a. Car lift – Hydraulic
b. Jackhammer – Pneumatic
c. Jaws of life tool – Hydraulic
d. Back hoe - Hydraulic
3. Identify five industries where the properties of fluids play an important role. For each industry,
provide an example of fluid use.
a. Food Industry: Manufacturing of products such as chocolates, syrups, and candies (viscosity)
b. Aviation Industry (flight): Hydraulic cylinders on airplane landing gear; Knowledge of properties of
air (fluid) are necessary for flight
c. Automotive Industry (cars): Hydraulic systems in brakes and steering; Alternative fuel sources
such as propane and hydrogen (fluids)
d. Construction: Hydraulic systems in equipment such as cranes and back hoes
e. Shipping: Knowledge of properties of fluids are necessary for safe loading and cargo; Ballast water
systems (buoyancy and density)
4. Identify each of the following as either mass or weight.
a. This measures the amount of matter in an object. MASS
b. This measures the force of gravity acting on an object. WEIGHT
c. This measurement varies according to the location of the object in the universe. WEIGHT
d. Unless something is added to or taken away from the object, this measurement of an object
remains the same everywhere in the universe. MASS
e. This pulling force is measured in newtons. WEIGHT
f. This measurement is not a force. MASS
5. Compare how a submarine, a fish, and a scuba diver control their depth in the water. Explain each in
detail – what does each one do in order to become less buoyant? And what about more buoyant?
a. Submarines: Ballast tanks fill with water to become more dense and to sink down; ballast tanks
release/empty water in order to become less dense and rise up again.
b. Fish: Swim bladders take in air to become less dense and rise up; Swim bladders release air and
become more dense and sink down.
c. Scuba Divers: Weight belt helps balance out buoyancy; BCD (Buoyancy Compensation Device) is
like a vest or life jacket – divers pump air into the vests to become more buoyant (less dense) to
rise up, and release the air to become less buoyant (more dense) to dive down.
Kluge 2012
NAME: _______ANSWERS________ HOMEROOM: _____
SCI 8: Fluids
6. Using the Particle Theory of Matter, explain the effects of temperature changes on solids, liquids, and
gases. Draw a diagram to support your explanation.
SOLID
Particle
Distribution
Strength of
particle bonds
Particle
motion
Particles in solids are very
close together
The bonds between particles in
solids are very strong
Particles in solids have very
little motion; they only vibrate.
Density
Solids usually have a greater
density than liquids and gases
Mass
Solids usually have a greater
mass than liquids and gases.
Volume
Changes in
Density due to
Temperature
Solids keep their own shape
when put into a container; they
take up the smallest amount of
volume.
When you add heat to a solid,
its density decreases
When you remove heat, its
density… increases
LIQUID
Particles in liquids are farther
apart than in a solid, but closer
than in a gas.
The bonds between particles in
liquids are stronger than gases,
but weaker than solids
Particles in liquids move
around very little
The density of liquids is
usually in between that of
solids and gases
The mass of liquids is usually
in between that of solids and
gases.
Liquids take on the shape of a
container, but they do not fill
out the whole container
GAS
Particles in a gas are quite spread
out.
The bonds between particles in
gases are quite weak
Gas particles have a lot of
motion; they move around fast
and bounce into one another
Gases usually have a lower
density than solids and liquids.
Gases usually have a lower mass
than solids and liquids.
When you add heat to a solid,
its density decreases
Gases take on the shape of a
container and they take up/fill out
the entire space of the container
that they are placed in.
When you add heat to a solid, its
density… decreases
When you remove heat, its
density… increases
When you remove heat, its
density… increases
7. Fill in the blanks to complete the sentences.
a. The ___flow rate______ of a fluid is an indicator of its viscosity.
b. Because the volume of a liquid under pressure changes very little, the liquid is said to be virtually
____incompressible_____.
c. Helium balloons float in air because their ___density___ is less than that of air.
d. Mechanical systems that use fluids to transmit force and move objects are called
__hydraulic_____ or ___pneumatic_____ machines, depending on the fluid used.
e. __Hydraulic___ machines use liquids and ___pneumatic_____ machines use gas.
f. The buoyant force is opposite the __gravitational____ force on an object in water.
8. A warning on an aerosol can states “Caution, container may explode if heated.” Explain why this might
be using the Particle Theory of Matter.
Kluge 2012
NAME: _______ANSWERS________ HOMEROOM: _____
SCI 8: Fluids
If the aerosol container is placed near a heat source, then the substance inside increases in
temperature, which causes the bond strength between particles to weaken, and the particles to
move faster. The more heated it becomes, the faster the particles move, and the faster the particles
move, the more collisions between them and the walls of the container there are. The more
collisions there are between particles, the more pressure builds up inside the aerosol container, and
if the pressure builds up enough, then it can explode.
9. Fill out the table below to describe the relationship between the following fluid properties.
Bond Strength
Volume
Density
Viscosity
Pressure
As Temperature
Increases
Decreases
(become
weaker)
Increases
(takes up more
space)
Decreases
(becomes less
dense)
Decreases
(becomes less
viscous)
Increases
(more
collisions)
As Temperature
Decreases
Increases
(become
stronger)
Decreases
(takes up less
space)
Increases
(becomes
more dense)
Increases
(becomes
more viscous)
Decreases
(less
collisions)
10. What are two ways in which the pressure of a confined fluid can be increased?
a. Increase temperature – As temperature is increased, bond strength decreases, and particles move
around faster; the faster the particles move, the more collisions there are between particles and
between the particles and the walls of the container; the more collisions there are, the greater
the pressure inside the container.
b. Compress the fluid - The more you compress a fluid, the less volume/space there is available for
it, and the less space there is available for the particles moving around, the more often these
particles collide with each other and with the walls of the container; the more collisions there are,
the greater the pressure inside the container.
11. What are the four parts of the Particle Theory of Matter?
a. All matter is made up of tiny particles too small to be seen
b. These particles attract each other
c. These particles are constantly in motion (moving around) because they have energy
d. The more energy the particles have, the faster they move (i.e., when you add heat energy, the
particles move faster)
Kluge 2012