Chapter 9 Review
Modified True/False
Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true.
____
1. Mass and weight are interchangeable terms.
____
2. A freighter on Lake Superior will float lower in the water than an identical freighter carrying the same load
on the Atlantic Ocean.
____
3. Buoyant force pushes objects in a direction opposite to the force of gravity.
____
4. The upward force exerted on objects submerged in fluids is called buoyant force.
____
5. As you drive into a deep valley, the "pop" you might hear in your ears is due to balanced forces.
____
6. Hydraulic systems that deliver water to high-rise apartment buildings counteract the force of gravity.
____
7. Heavy loads of gravel are lifted into trucks by front-end loaders. A liquid pumped into the arms of the bucket
moves the bucket of the loader up and down, making the bucket a good example of a pneumatic system.
____
8. Force is anything that causes a change in the motion of an object.
____
9. Archimedes’ principle states that the buoyant force acting on an object equals the volume of the fluid
displaced by the object.
____ 10. Compressibility is the ability to be squeezed into a smaller volume.
____ 11. A liquid becomes compressible when it is enclosed in a tube or pipe.
____ 12. When gases are compressed, their volume decreases.
____ 13. One of the properties of liquids is that they are easily compressed.
____ 14. The device known as the Jaws of Life™ illustrates how powerful pneumatic systems can be.
Completion
Complete each statement.
15. In order for a hot-air balloon to rise, the __________________________ exerted by the air particles inside the
balloon must exceed the balloon's weight.
16. If you hiked up a mountainside, the air pressure would ____________________ as you ascended.
17. The thin membrane (shown here) is the eardrum. It responds to changes in ____________________ outside
the body.
18. _______________ law states that pressure exerted on a contained fluid is transmitted in all directions
throughout the fluid.
19. Hydraulics is the study of pressure in _____________.
20. ____________________ is the study of pressure in gases.
21. Your heart and circulatory system make up a complex ____________________ system.
22. The pull of gravity on an object is called the _______________________ of the object.
23. Average _______________________ is the total mass of an object divided by the total volume.
24. Archimedes' principle states that the _______________________ force acting on an object equals the weight
of the fluid displaced by the object.
25. A _______________________ is used to measure the density of a liquid.
26. The volume of an irregularly shaped object (such as a flower) can be measured using
_______________________ principle.
27. The unit for measuring pressure is the _______________________ .
28. Because solids and liquids cannot be squeezed into a smaller volume, they are said to be almost
_______________________ .
29. An aquarium that has a base area of 2 m2 and weighs 50 000 N exerts _______________________ kPa of
pressure on its stand.
30. Gases and liquids respond differently when the same force is applied to them. _______________________
can be easily compressed, while _______________________ will only change slightly in volume.
31. Hydraulic systems are devices that transmit applied force through a _______________ to move something
else.
32. _____________________________ are devices in which a gas is used to transmit force.
Matching
Match the correct term to each of the following characteristics.
a. neutral buoyancy
e. swim bladder
b. average density
f. pascal
c. hydraulic multiplication
g. density
d. Newton
h. ballast tank
____ 33. can be lowered for a person by wearing a life jacket
____ 34. part of the depth-control structure of a submarine
____ 35. unit of measure for buoyant force
____ 36. organ containing a mixture of air and water
____ 37. occurs when force of gravity and buoyant force are equal
Match the correct term to each of the following actions.
a. constant
d. liquid
b. hydraulic system
e. gas
c. incompressible
____ 38. transmits applied force through a liquid to move something
____ 39. state of matter used in pneumatic systems
____ 40. describes pressure in a hydraulic system
____ 41. a characteristic of liquids that makes them effective in hydraulic systems
____ 42. state of matter used in hydraulic systems
Short Answer
43. Explain how a flotation device such as a life jacket helps a person to float.
44. Use your knowledge of pressure to explain why people's ears sometimes hurt when they swim underwater.
45. Give two examples of a situation in which a person might experience a change in pressure with depth or
altitude.
Problem
46. Calculate the pressure when a 100 N force is exerted on a hydraulic pump over the following areas. Show
your work.
a) A = 25 cm2
b) A = 20 cm2
c) A = 10 cm2
d) A = 5 cm2
e) Plot your results on a graph.
f) What do these results tell you about how hydraulic pumps operate?
47. A huge indoor shopping mall has just opened a new entertainment feature - a children's submarine ride.
During your interview for a part-time job as a submarine operator, the manager asks you to explain
a) how you would adjust the depth of a submarine, and
b) what scientific property would be at work during that operation.
How would you respond?