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Unit 1 Force in a Mechanical System
True/False
1. Torque is rotation only in the counter clockwise (ccw) direction.
2. Force is a scalar quantity.
3. A force can change the shape of an object.
4. If opposing forces are equal it is balanced.
5. Another term for balanced forces is equilibrium.
Multiple Choice
6. If two forces of the same magnitude act on an object along the same line, but in opposite directions, the object
is said to be ____________________.
a. speeding up
b. in equilibrium
c. slowing down
d. unbalanced
7. Torque is defined as _____________________________________________________.
a. the product of the length, measured in pounds, and the force, measured in feet
b. the product of the force applied and the length of the lever arm
c. the product of the force, measured in pounds, and the length, measured in Newtons
d. the speed at which a body rotates
8. The torque exerted on the driven gear in the following diagram is __________. (Remember T = FL.)
a. 22 lb·ft
c. 10 lb·ft
b. 40 lb·ft
d. none of these
9. The torque of a system whose force (F) is 30 lbs and length (L) is 2 ft is _________.
a. 60 lbs
b. 15 lbs
c. 60 lb·ft
d. 15 lb·ft
10. Which of the following is being described as a vector?
a. 0 degrees Celsius
b. 148 miles per hour, North
c. 125 Newton
11. Heat moves ___________________.
a. from cool areas to warm areas
b. from warm areas to cool areas
12. Weight can be measured with ______________.
a. a spring scale
c. a triple-beam balance
b. a ruler
d. a graduated cylinder
13. The amount of matter that a certain object contains is called its _____________.
a. weight
b. toque
c. vector
d. mass
14. The unit of force in the English system is the _________.
a. pound
b. Newton
c. inch
d. ft·lb
15. Force is __________.
a. a push
b. a pull
c. a vector
d. both a and b
16. If you were on the moon, your __________ would be the same as on the earth.
a. mass
b. weight
c. torque
17. In order to double the torque you could find a torque wrench with a handle __________________________.
a. twice as long as the original wrench
b. half as long as the original wrench
c. three times as long as the original wrench
d. you do not need to change the length of the handle
18. If you push a lawn mower and it moves, the force on the lawn mower is ______________.
a. balanced
b. unbalanced
19. The unit for mass in the SI system is ___________.
a. lbs
b. lb·mass
c. kg
d. N
20. Torque equals the applied force times the lever arm. What would the torque be if the force on the lever is 10
ft·lbs and the lever is 10 ft in length?
a. 10 ft·lb
b. 100 ft·lb
c. 0 ft·lb
d. 20 ft·lb
21. What would be the resultant force on a machine if there is a pushing force of 10 ft·lbs in one direction and
there is a pulling force of 10 ft·lbs in the opposite direction?
a. 100 ft·lb
b. 20 ft·lb
c. 10 ft·lb
d. 0 ft·lb
22. Force is another name for ______________.
a. motivation
c. what Luke Skywalker tried to promise
b. a push or a pull
d. torque
23. When forces are in equilibrium an object in motion ________________________.
a. moves slowly
b. could start to rotate
c. slows down
d. moves in a straight line at constant speed
24. Which of the following is a vector?
a. time
b. your age
c. temperature d. force
e. mass
25. Indicate which of the following is an example of force in equilibrium.
a. All forces acting on a body are equal
c. A moving object continues moving at the
same speed and in the same direction
b. An object at rest remains at rest
d. all of the above
Unit 2 Pressure in a Fluid System
True/False
26. Fluids always move from regions of low pressure to regions of high pressure.
27. If the weight of a ship is greater than the buoyant force the ship will sink.
28. Gage pressure is the total pressure measured above atmospheric pressure.
29. Hydraulics or liquids are the classifications of all fluid systems.
30. PSI is a unit of pressure.
31. Atmospheric pressure is approximately 15 psi.
32. Liquids or gasses move in a fluid system when pressure difference exit between different points in the system.
Multiple Choice
33. All fluid systems can be classified as either _______________________.
a. solid or liquid
c. pneumatic or hydraulic
b. hydraulic or liquid
d. pneumatic or gas
3
34. If 10 cm of a substance has a mass of 105gm, what is its density?
a. 1050 gm/cm3
b. 1050
c. 10.5 gm/cm3
d. 10.5
35. Which of the following is the most complete definition of buoyant force?
a. The apparent weight of an object that floats in water.
b. The upward force on an object that is equal to the weight of the fluid displaced by that
object.
36. A submarine is located at a depth of 100 feet. If a column of sea water one foot high and one square inch in
cross-sectional area weighs 0.443lb, what is the pressure exerted by the sea water n the submarine’s hull?
a. 100 lb/in2
b. 59.13 lb/in2
c. 29.73 lb/in2
d. 44.3 lb/in2
37. A storage tank is filled to a depth of 25 feet with an alcohol that has a weight density of 58.5 lb/ft3. What is
the pressure at the bottom of the tank? (Remember:
.)
a. 10.2 lb/ft2
b. 1462.5 lb/ft2
c. 46,800 lb/ft2
d. 325 lb/in2
38. A simple U-tube manometer filled with mercury (
lb/in3) is connected between two bottles of gas
with different pressures. The difference in height between the two columns of mercury is 14.3 inches. What
is the difference in pressure between the two bottles of gas? (Remember :
.)
a. About 7 psi
b. 29.2 psi
c. 36.32 mm of Hg d. 3.43 in/lb
39.When the valve is opened between the two tanks shown here, in which direction will the fluid move?
a.
b.
c.
d.
The fluid will move from left to right.
The fluid will move from right to left.
The fluid will not move at all.
The fluid will move up in both tanks.
40. A net pressure is like a net force in that ______________________________________.
a. a net pressure causes fluid to move just as a net force causes objects to move
b. a sealed container may change its shape due to a net pressure
c. a net pressure is measured in units of Newtons, just like a force
d. a and b
41. A hydraulic system is a fluid system that uses _________ as the fluid.
a. gas
b. air
c. liquid
d. solid
42. If you took an air pressure reading on your bicycle tires and read 50 lb/in , you would be reading
_________________.
a. atmospheric pressure
c. total pressure
b. absolute pressure
d. gage pressure
43. The instrument used to measure gas pressure and pressure difference between two points in a system is a
________________.
a. manometer
b. tire gage
c. hydraulic jack
d. hydrometer
44. The most likely fluid system to use in lifting a truck would be a __________________.
a. pneumatic system
b. hydraulic system
c. thermal system
45. The deeper an object goes underwater the greater the ___________.
a. mass
b. pressure
c. volume
d. density
46. Absolute pressure is the ___________ pressure measured above a reference of zero pressure.
a. above
b. air
c. total
d. none of these
47. ______________ is a fluid system that uses air or gas as a fluid.
a. Gage
b. Density
c. Pneumatic
d. Hydraulic
48. What is the English unit for density?
a. lb/ft
b. lb/ft
c. kg/m
d. g/cm
49. Which of the following statements about pressure is not true?
a. Every pressure system contains a fluid—either a liquid or a gas.
b. The pressure difference in the system causes a directional move.
c. The pressure flows from high to low.
d. Movement in a pressure system occurs when no pressure difference occurs.
50. What substances are considered fluids?
a. gases only
b. liquids only
c. gases and liquids
Unit 3 Voltage in an Electrical System
Completion
A
Alternating
AC
Conductor
neutrons
B
electrons
DC
switch
DC
C
attract
Battery/cell
load
positive
D
repel
negative
voltage source
neutral
Identify the numbered parts in the electrical circuit below.
51. 1. __________
52. 2. __________
53. 3. __________
54. 4. __________
55. When frequency and hertz are used to describe electrical current, they are describing ______________
voltage.
56. When electrical charge moves back and forth through a conductor, it’s called ____ current.
57. When batteries are connected in series, the positive terminal of one battery should be connected to the
____________ terminal of the other battery.
58. When electrical charge moves continuously in one direction through a conductor, it’s called ____ current.
59. Here are two types of electricity: direct current (DC) and alternating current (AC). The type of electricity
found in you typical flashlight battery is ___________.
Multiple Choice
60. Any material that permits the movement of electrical energy through it is called a(n) ________________.
a. electrical load
b. switch
c. conductor
d. electrode
61. In electrical systems, voltage acts as _______________.
a. pressure
b. energy
c. work
d. prime mover
62. Voltage is considered a force-like quantity because it ________________________.
a. is found in electrical circuits
b. pushes conductors around the circuit
c. acts as a prime mover of electric charge
63. Which of the following is not an example of an electrical load?
a. light bulbs
b. television sets
c. hair dryers
d. batteries
Use the following diagram to answer the questions below.
64. When putting batteries together in series you should connect the leads so that they are
a. positive to positive
c. negative to negative
b. positive to negative
d. it doesn’t matter
65. Which circuit above represents a good connection?
a. The circuit on the right
c. The circuit on the left
b. Both circuits
d. Neither circuit
66. What type charge do electrons have?
a. negative
b. positive
c. neutral
67. _____________ is the unit for voltage.
a. Anode
b. Amp
c. Pascal
d. Volts
68. What is the frequency of the electricity we get from household outlets?
a. 120 volts
b. 60 volts
c. 120 hertz
d. 60 hertz
69. Electrons flow from ______________________________.
a. positive to negative
b. negative to positive
c. they don’t flow
d. first negative to positive then positive to negative
70. Movement of an electrical current in one direction through a conductor is called ___________________.
a. current
c. direct current
b. alternating current
d. indirect current
71. A class of batteries that are rechargeable is called ______________.
a. primary cell
b. secondary cell
c. chemical cell
d. dry cell
True/False
72. The main source of DC electricity is electrical generating plants.
73. When you put three 6V batteries together in series you will have 12V running through the circuit.
74. The electrical forces “rule of attraction” is “like charges attract and unlike charges repel”.
75. Batteries produce AC.
Unit 4 Temperature in a Thermal System
True/False
76. Temperature is scalar.
77. Thermal systems are designed to move heat energy from warmer regions to cooler regions.
78. When you take a temperature you actually are measuring the average energy of motion of the molecules of a
substance.
79. 40° Celsius is very cold.
80. On the Celsius temperature scale water freezes at 32oC
Multiple Choice
81. A thermocouple thermometer works because a voltage difference is generated between two junctions that are
at different temperatures. The two junctions are made of _______________________________.
a. two pieces of wire of the same material
b. three pieces of wire of the same material
c. three pieces of wire of two different materials
d. two wires made of different materials
82. The temperature inside a house is 70 F. Outside the house the temperature is 40 F. The temperature
difference is _________.
a. 30 F°
b. 30°F
c. 110 F°
d. 110°F
83. Heat describes ___________ energy in matter.
a. potential
b. molecular
c. electric
d. nuclear
84. Heat moves from regions of ______________________.
a. lower to higher temperatures
c. equal temperatures
b. higher to lower temperatures
d. extreme temperatures
85. Which is larger?
a. 1 C°
b. 1 F°
86. The force-like quantity in thermal systems is _________________.
a. an insulator
b. a conductor
c. heat continue
d. T
87. What temperature measuring device can measure the temperature of molten aluminum?
a. thermocouple
c. thermostat
b. liquid and glass thermometer
88. Heat is a measure of what form of energy?
a. temperature
b. vibrating motion of atoms and molecules
c. the sun
89. A thermocouple is used to ____________________________.
a. measure a temperature difference
c. confuse students
b. find two people on a hot date
d. measure the length of two wires
90. The liquid in a thermometer ___________ as temperature increases.
a. rises
b. falls
c. remains the same
91. Which of the following is not true about temperature?
a. Temperature is scalar (magnitude, but no direction).
b. Temperature can be measured in degrees Celsius and Fahrenheit.
c. Temperature depends on the presence or absence of heat
d. Temperature is a descriptive word that refers to energy found in the vibrating molecules.
92. In a room, heat from a space heater will travel __________________________________.
a. from the warmer area around the heater, to the cooler area of the room
b. from the cooler area of the room to the warmer area of the room
c. from the ceiling to the floor
93. The reason that we insulate our home is __________________________.
a. to reduce heat loss in the winter
b. to reduce heat gain in the summer
c. both a and b
94. Each degree on the Fahrenheit temperature scale is _________________ compared to a degree on the Celsius
temperature scale.
a. larger
b. smaller
Completion
A
100
100oC
higher, lower
F
B
180
100Co
lower, higher
temperature
C
40oC
heat
T
temperature difference
D
40Co
thermocouple
temp
heat transfer
95. Heat always moves from regions of ___________ temperature to regions of __________ temperature.
96. When you measure the average energy of motion of the molecules of a substance, you are measuring its
_____________.
97. The symbol for temperature difference is ________.
98. A measure of the average energy of motion of the molecules in a substance is termed _______________.
99. A temperature of 100 Celsius degrees would be written as ______.
100. A Celsius temperature difference of 40 degrees would be written as _____.
Unit 5 Work in a Mechanical System
True/False
101. 1 radian = 57.3 degrees.
102. Work is done on a car by a parking brake that is keeping it from rolling down a hill.
103. Mechanical work is done only when a force or torque moves an object.
104. A construction crane applying a 1000 lb force on a 5 ton I-beam is doing mechanical work.
105. When air keeps a bike tire inflated, the amount of work is equal to the pressure in the tire.
Multiple Choice
106. A special airport truck is used to push a heavy airliner away from the terminal. The truck pushes with a force
of 2000 lb for a distance of 150 ft. The mechanical work done by the truck is ____________.
a. 30,000 ft·lb
b. 300,000 ft/lb
c. 300,000 ft·lb
d. 30,000 ft/lb
107. A ninety degree angle is equal to ____.
a.
b. 4 rad
c.
d. 2 rad
rad
rad
108. An SI unit for work is _________.
a. N·m
b. ft·lb
c. N
d. kg
109. You are using a winch to pull your boat out of water. To calculate the work put into the winch you should use
which formula?
a. Work = force distance
c. Work = pressure difference volume
b. Work = torque angle swept
d. Work = voltage current
110. The formula for calculating efficiency is ____________________.
a.
c.
b.
d.
1
111. Work is done on a barbell when it is _____________.
a. resting on the floor
b. held steady by the lifter after it is raised
c. moving during the lift
112. Work is being done by a football passing quarterback _____________________________.
a. when the ball is on the ground
b. during the throwing motion of the quarterback’s arm with the ball in his hand
c. while the ball is sailing through the air
113. How many radians (rads) are there in a 360 degree circle?
a. 3.24 rads
b. 57.3 rads
c. 6.28 rads
d. 360 rads
114. Which of the following descriptions match the definition of work?
a. A winch pulling a truck out of a ditch.
b. An escalator transporting people to a new floor.
c. A pitcher throwing a 90 mph fast ball.
d. All of the above are descriptions of the work definition.
115.Two students push on a car for 15 minutes to try to get it out of the ditch they drove it into. The car is stuck so
deep in the mud that it doesn’t even budge. How much work has been done on the car by the students?
a. 30 joules
c. none
b. 30 ft·lbs
d. there isn’t enough information to know
116. Another name for a Newton-meter is ______________.
a. radian
b. joule
c. torque
d. force
117. How much work is done when a winch lifts 50 lbs a distance of 1 foot off the floor?
a. 500 ft/lbs
b. 50 ft·lbs
c. torque
d. 100 ft·lbs
118. When adding more pulleys to a system, _______________________________.
a. the force of the weight increases.
c. the pulling force increases.
b. the force of the weight decreases.
d. the pulling force decreases.
Completion
A
input work
N·m
6.28
work
B
40
ft·lb
efficiency
torque
C
joule
radians
20
distance
D
moves
length
3.14
angle
119. The work unit of one joule is also equal to one _________________.
120. When a torque causes a rotation through an angle, the size of the angle can be expressed in degrees or in
__________.
121. Work is measured in _________________ in the English system.
122. 40 N·m = ____ joule
123. One revolution is equal to ____ radians.
124. Efficiency is expressed as output work divided by _________________.
125. To figure mechanical work one must know the force and __________________________.
Problems:
The values given below can be classified as either scalar or vector quantities. Examine each value and write
“vector” or “scalar” for each on a separate sheet of paper.
____ 1. 15 Newtons at 30° east of north
____ 2. 30°C
3. John pushes on a box with a force of 6 lbs. Sue gets on the other side and pushes with a force of 8 lbs. What
is the net force on the box?
4. Using the scale of “one division = 20lb of force,” find the value of the resultant force and direction (FR) in the
diagram shown.
5. What is the density of a rock that weighs 75 grams and has a volume of 30 cm?
6. Aluminum has a density of 2.7g/cm3. Find the mass of a 100 cm3 piece of Aluminum.
7. The density of lead is 11.3 g/cm , what is its specific gravity?
8. A wheel diameter is 1 ft and a force of 60 lbs is applied. What is your torque?
9. A torque wrench has a lever arm of 2 ft. A force of 35 lb is applied to the end of the wrench to tighten a bolt.
What is the torque applied to the bolt?
10. If the lever arm is 8 inches long and you apply 66 lbs of force to it what is the torque?
11. Convert 21°C to °F using °F = 1.8(°C) + 32.
12. The temperature of a skillet is measured to be 350°F. What is its temperature in Celsius degrees?
A block and tackle is used to lift a load weighing 800 lb. The operator lifts the load a distance of 1.50 ft
by pulling on the rope with a force of 200 lb over a distance of 4 ft.
13. Input work = ____ ft·lb
14. Output work = _______ ft·lb
15. Efficiency of block and tackle = ______%
Short Answer
1. Give an example of how work is done in a mechanical system of your choice.
2. Briefly describe one situation in which a technician is required to measure and apply force in some part of a
mechanical system.
3. Give a brief description of a situation where a technician must control temperature.
4. Explain how a typical liquid-in-glass thermometer works to measure temperature.
5. Briefly describe how a technician might measure or control pressure in a fluid system.
6. Briefly describe a circumstance that requires a technician to measure voltage.
7. Please draw a schematic diagram of the electrical hookup above. Include the battery, switch, conductors, and
electrical load.
8. Together, Misty and Jason are pushing a shopping cart down the middle of the grocery aisle. John is applying
2 lbs of force while Jane is applying 4 lbs of force. Explain what is going to happen to this shopping cart as
they push it down the aisle.
9. Think about the forces acting on your body right now. Are they in equilibrium? Prove that your answer is
correct.