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Final Review

True/False
Indicate whether the statement is true or false.
 

 1. 

Work is done on a car by a parking brake that is keeping it from rolling down a hill.
 

 2. 

A construction crane applies a 1000 lb force on a 5 ton I-beam, doing mechanical work?
 

 3. 

When air keeps a bike tire inflated, the amount of work is equal to the pressure in the tire.
 

 4. 

Liquids and gases tend to move from areas of low-pressure to areas of high-pressure.
 

 5. 

A sewer system is an example of a closed fluid system.
 

 6. 

When a hydraulic cylinder moves, it displaces a volume of fluid.
 

 7. 

In a fluid system work is done when a pressure difference causes liquids or gas to move.
 

 8. 

The basic unit of an electrical charge is the coulomb.
 

 9. 

Voltage differences cause a charge to move.
 

 10. 

Electricity is not a very efficient way to transport energy.
 

 11. 

In devices such as rotating motors, radios, and coffee pots, we can’t actually see the electrical work being done.  We can only see the results of electrical work.
 

 12. 

Speed is a scalar quantity
 

 13. 

The equation for linear speed is tf013-1.jpg.
 

 14. 

The speed of an object is its velocity
 

 15. 

When a car slows to a stop sign its acceleration changes.
 

 16. 

tf016-1.jpg is used to figure the time it takes to move a volume.
 

 17. 

It would not be important for the manager of a city water treatment plant to know the flow rate of water through the system.
 

 18. 

Locating compressed air sources (storage tanks or compressors) near the point of use makes no difference on flow rate.
 

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 19. 

Work is equal to force applied to an object ______________ the distance the object moves in the direction of the applied force.
a.
plus
b.
minus
c.
multiplied by
d.
divided by
 

 20. 

Useful work is defined is applied force mc020-1.jpg _________.
a.
mass
b.
distance
c.
weight
d.
density
 

 21. 

An SI unit for work is _________.
a.
N·m
b.
ft·lb
c.
N
d.
kg
 

 22. 

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 mc022-1.jpg distance
c.
Work = pressure difference mc022-3.jpg volume
b.
Work = torque mc022-2.jpg angle swept
d.
Work = voltage mc022-4.jpg current
 

 23. 

The SI unit for work is _______.
a.
ft·lb
b.
N/m
c.
Joule
d.
lb/ft
 

 24. 

The formula for calculating efficiency is ____________________.
a.
mc024-1.jpg
c.
mc024-3.jpg
b.
mc024-2.jpg
d.
mc024-4.jpg
 

 25. 

One radian is equal to ________.
a.
360 degrees
b.
57.3 degrees
c.
2p radians
 

 26. 

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
 

 27. 

When mechanical work is done on an object _______________________.
a.
the object remains stationary
c.
the object remains at rest
b.
the object must move
d.
the object disappears
 

 28. 

GIVEN:  mc028-1.jpg
 mc028-2.jpg
A block and tackle is used to raise a deer weighing 250 lbs a distance of 2 feet.  The hunter pulls with a force of 100 lbs for 6 feet.  Find the efficiency of the block and tackle.
a.
67%
b.
75%
c.
83%
d.
92%
 

 29. 

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
 

 30. 

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
 

 31. 

Which of the following is not a SI system of measuring work?
a.
ft·lb
b.
joule
c.
N·m
 

 32. 

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.
 

 33. 

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
 

 34. 

If the output work is divided by the input work in a mechanical system, the result is ______________.
a.
efficiency
b.
work
c.
power
d.
force
 

 35. 

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.
 

 36. 

The work done by a moving piston in a hydraulic cylinder is equal to the pressure exerted by the piston multiplied by the ______________________.
a.
area of the piston face
b.
fluid volume displaced
c.
weight density of the fluid
 

 37. 

A pump lifts 2 cubic meters of water through a pressure difference of 200,000 N/mmc037-1.jpg.  The fluid work done by the pump is _______________.
a.
400,000 N/m
b.
400,000 N·m
c.
100,000 N/m
d.
100,000 N·m
 

 38. 

A hydraulic cylinder displaces 0.25 ftmc038-1.jpg of oil while the piston moves a distance of 1 ft.  The pressure on the face of the piston is 60 lb/ftmc038-2.jpg.  The work done by the hydraulic cylinder while moving the piston 1 ft is __________.
a.
60 ft·lb
b.
60 ft/lb
c.
15 ft·lb
d.
240 ft·lb
 

 39. 

Work done by a hydraulic cylinder is ____________ work.
a.
mechanical
b.
fluid
c.
electrical
d.
thermal
 

 40. 

What is the fluid work done by a pump that lifts 100 ftmc040-1.jpg of water through a pressure difference of 5000 lb/ftmc040-2.jpg.
a.
500,000 N·m
b.
500,000 lb/ft
c.
500,000 ft·lb
d.
50,000 ft·lb
 

 41. 

A hydraulic cylinder rod is displaced 1 ft by a pressure of 100 lb/ftmc041-1.jpg.  What is the work done if 0.5 ftmc041-2.jpg of fluid is displaced?
a.
50 N·m
b.
50 ft·lb
c.
200 ft·lb
d.
100 ft·lb
 

 42. 

In a fluid system, work is done when _________________________________.
a.
we inhale and expand our lungs
b.
a pressure difference causes liquids or gases to move
c.
water is pumped through a control valve, moving a piston
d.
all of these
 

 43. 

An open fluid system moves fluids, but ____________ retain and recirculate the fluids throughout the system.
a.
does
b.
does not
 

 44. 

What is the quantity moved in a fluid system?
a.
weight
b.
distance
c.
volume
d.
density
 

 45. 

Which of the following is an equation for work done in a pressure system?
a.
mc045-1.jpg volume displaced
b.
W = pressure difference mc045-2.jpg V
c.
both a and b are equations for work done in a pressure system
 

 46. 

Which of the following is a closed system?
a.
a person using a drinking straw
b.
a thermometer
c.
an automobile gas tank
d.
a human digestive track
e.
lake water flowing over a dam
 

 47. 

Which of the following is an open fluid system?
a.
the human circulatory system
b.
an automobile cooling system
c.
the coolant in a refrigeration system
d.
an automobile windshield washer system
e.
an automobile brake system
 

 48. 

Which of the following is not true?
a.
fluids flow from low pressure to high pressure
b.
fluids flow uphill only if work is done
 

 49. 

What type of work does the work equation mc049-1.jpg represent?
a.
mechanical work
b.
electrical work
c.
fluid work
d.
thermal work
 

 50. 

Work done in fluids can be calculated by using which of the following?  (Note: there may be more than on correct answer.)
a.
mc050-1.jpg
c.
mc050-3.jpg
b.
mc050-2.jpg
d.
mc050-4.jpg
 

 51. 

In electrical work, the displacement-like quantity is the charge that’s moved.  The force-like quantity is __________________.
a.
the voltage difference
c.
measured in joules
b.
the product of the current and time
d.
measured in newtons
 

 52. 

The coulomb is a unit of electrical charge that’s equal to _______________.
a.
one ampere
c.
60 ampere-seconds
b.
the charge on 6.25 mc052-1.jpg 10mc052-2.jpg electrons
d.
one ampere-second
 

 53. 

A 1.5-volt battery delivers 6 coulombs of charge.  How much work has it done?
a.
4 ampere-hours
b.
9 joules
c.
4 joules
d.
9 newtons/meter
 

 54. 

An electrical motor does 800 N·m of useful mechanical work while it uses up 1000 joules of electrical energy.  The efficiency of this motor is ______.
a.
100%
b.
125%
c.
80%
d.
none of these
 

 55. 

A 12-volt battery does 180 V·C of work.  How much charge has it moved? 
a.
2160 coulombs
c.
9.375mc055-2.jpg coulombs
b.
7.813mc055-1.jpg coulombs
d.
15 coulombs
 

 56. 

A 220V electric motor draws a current of 40 amperes for five seconds. 
How many coulombs of charge are moved? 
Remember, charge (q) = current(I)mc056-1.jpgtime(t).
a.
8 coulombs
b.
5.5 coulombs
c.
55 coulombs
d.
200 coulombs
 

 57. 

Electricity can do useful work by _______________________.
a.
doing mechanical work
c.
producing light
b.
producing heat
d.
all of these
 

 58. 

The positive charge is carried by _______________.
a.
protons
b.
electrons
c.
neutrons
 

 59. 

Electrical work is equal to _________________________.
a.
volts mc059-1.jpg force
c.
volts mc059-3.jpg coulombs
b.
coulombs mc059-2.jpg mass
d.
joules mc059-4.jpg coulombs
 

 60. 

AC electricity is produced by a _______________________.
a.
alternator
b.
generator
c.
motor
 

 61. 

1 amp second equals _________________.
a.
1 joule
b.
1 coulomb
c.
1 volt
d.
1 watt
 

 62. 

The force-like quantity that moves electrical charge is measured in ________________.
a.
amperes
b.
joules
c.
coulombs
d.
volts
 

 63. 

The movement or flow of an electric charge is called ________________.
a.
proton
b.
negative charge
c.
current
d.
shock
 

 64. 

Why do we produce electricity to do work when the process is only 60% efficient?
a.
electricity is an efficient way to transport energy
b.
electricity is clean
c.
electricity is convenient and easy to use
d.
all of these
 

 65. 

A coulomb of charge is equal to _________________________.
a.
6.25 mc065-1.jpg 1018 electrons
b.
a unit of electrical charge
c.
represented by q in the equation mc065-2.jpg
d.
all of these
 

 66. 

An electrical system produces 1000 Joules of work output by using 1500 Joules of input.  The system has an efficiency percentage of _____.
a.
150%
c.
500%
b.
66.7%
d.
none of these are even close
 

 67. 

In the formula mc067-1.jpg, what does the q stand for?
a.
voltage difference that moves the charge
c.
quantity of charge moved
b.
pressure difference
d.
amount of electrical work
 

 68. 

In electrical systems 1 joule of work is also equal to ________________.
a.
1 volt-coulomb
b.
1 volt/coulomb
c.
1 coulomb/volt
d.
1 N/m
 

 69. 

A more efficient motor is one that works ___________________________.
a.
faster for the same work done
b.
at a higher voltage
c.
using fewer joules for the same work done
d.
using fewer coulombs for the same work done
 

 70. 

One joule is equivalent to ______________. 
a.
1 volt-coulomb
b.
1 radian
c.
1 ampere-hour
 

 71. 

An angular speed of 2 rpm can also be expressed as ________ rad/sec. 
(Hint: Remember that 1 min = 60 sec and 2p radians = 360°.)
a.
0.105
b.
0.209
c.
0.318
d.
0.636
 

 72. 

If the rate’s direction and magnitude are given the rate is a _________________.
a.
velocity
b.
speed
 

 73. 

Rate is defined as a displacement-like quantity divided by  ____________.
a.
distance
b.
time
c.
volume
d.
mass
 

 74. 

You traveled across the state of Nebraska, a distance of 550 miles in 12 hours. 
What was your average speed?
a.
50 miles/hr
b.
55 miles/hr
c.
45.8 miles/hr
d.
65 miles/hr
 

 75. 

360 degrees is equal to _______ radians.
a.
p
b.
2p
c.
3p
d.
4p
 

 76. 

Speed is a __________________.
a.
vector quantity
b.
scalar quantity
 

 77. 

Which of the following is an angular rate?
a.
merry-go-round
b.
helicopter blades
c.
hands on a clock
d.
all of these
 

 78. 

Which of the following equations best defines velocity?
a.
mc078-1.jpg
b.
mc078-2.jpg
c.
mc078-3.jpg
 

 79. 

The English unit for velocity is _________.
a.
m/sec
b.
ft/sec
c.
m/sec/sec
 

 80. 

Which symbols are used in linear equations?
a.
mc080-1.jpg
b.
mc080-2.jpg
c.
mc080-3.jpg
d.
mc080-4.jpg
e.
none of these
 

 81. 

Rates are used in which systems?
a.
mechanical
b.
fluid
c.
electrical
d.
heat
e.
all of these
 

 82. 

Which of the following is not a unit for linear motion?
a.
m/sec
b.
mi/hr
c.
ft/sec
d.
rpm
 

 83. 

A negative linear acceleration indicates that an object is _________________.
a.
slowing down
b.
speeding up
c.
changing direction
 

 84. 

Which of the following are rates? 
a.
mc084-1.jpg
c.
l = 2 m
b.
t = 3 sec
d.
mc084-2.jpg= 30 degrees
 

 85. 

Which symbols are used in rotational equations? 
a.
w
c.
t
b.
a
d.
all of the above
 

 86. 

If a leak in a faucet causes a water loss of 120 gallons in two days, what’s the volume-flow rate per hour (24 hours = 1 day)?
a.
6.0 gal/hr
b.
60 gal/hr
c.
2.5 gal/hr
d.
25 gal/hr
 

 87. 

An automobile air conditioner pumps 5 kg of Freon gas through the system in 3 minutes.  Find the mass-flow rate of the Freon per minute.
a.
0.6 kg/min
b.
1.7 kg/min
c.
12 kg/min
d.
15 kg/min
 

 88. 

The size of pipes that deliver fluids over long distances has a direct bearing on making the fluid available as needed.  This primarily has to do with _________________.
a.
volume-flow rate
c.
neither a nor b
b.
fluid speed control
d.
both a and b
 

 89. 

Common units for volume-flow rate are _____________.
a.
m3/sec
b.
ft3/sec
c.
gal/min
d.
all of these
 

 90. 

A swimming pool holds 20,000 gallons of water.  Using a hose, it takes 24 hours to fill the pool at a steady rate.  What is the volume-flow rate of water from the hose in gallons pre minute?
a.
11.9 gal/min
b.
12.9 gal/min
c.
13.9 gal/min
d.
14.9 gal/min
 

 91. 

An air conditioning system pumps 10 lbs of Freon through the system in 4 minutes.  Find the mass-flow rate of the Freon per minute.
a.
2 kg/min
b.
2.4 kg/min
c.
1.7 lb/min
d.
2.5 lb/min
 

 92. 

Compressed air should be ________________________.
a.
far from the source
b.
close to the source
c.
It doesn’t make any difference where it is located
 

 93. 

Volume flow rate equals _____________________________.
a.
volume of fluid moved divided by time of movement
b.
time of movement divided by volume of fluid moved
c.
volume of fluid moved multiplied by time of movement
 

 94. 

The equation for mass flow rate is ____________________.
a.
mc094-1.jpg
b.
mc094-2.jpg
c.
mc094-3.jpg
d.
mc094-4.jpg
e.
mc094-5.jpg
 

 95. 

A pipe delivers water at 3 gal/min.  If it takes 2.5 days to fill the pool, what volume is in the pool?
a.
180 gal
b.
562 gal
c.
1.08 mc095-1.jpg 104 gal
d.
5.37 mc095-2.jpg 104 gal
e.
6.48 mc095-3.jpg 105 gal
 

 96. 

Which of the following is a unit used for volume flow rate?
a.
kg/hr
b.
m/s
c.
l/min
d.
lb/min
 

 97. 

It is best to have an air compressor with a _______________________________.
a.
long hose, because this increases flow rate
b.
long hose, because this decreases flow rate
c.
short hose, because this decreases flow rate
d.
short hose, because a long hose decreases flow rate
 

Problem
 

 98. 

A simple mechanical winch has a crank handle one foot long.  A force of 10 lb is required to turn the crank.  How much work is done in turning the crank through 1 revolution?  (Remember that Torque = Force pr098-1.jpg Lever Arm.)
 

 99. 

How much work is done when a 150 lb student climbs up twenty five 8 inch stairs?
 

 100. 

A crane lifts a 2800 N concrete conduit 3 meters high.  Calculate the work required for this job.
 

 101. 

A manual car jack requires 1750 ft·lb to do its job.  The result of this work input is that 1500 lb of car is raised off the ground 1 foot.  What is the efficiency of the jack?
 

 102. 

A rusty nut moves with difficulty on an equally rusty threaded shaft.  It requires 5 lb of force continually applied a 10 inched from the center of the nut to turn the nut.  How much work is done in each revolution?
 

 103. 

Find the efficiency if output work equals 300 lb and input work equals 900 lb.
 

 104. 

Find the efficiency of a block and tackle when 2000 ft·lbs of work was used to do 1700 ft·lbs of work.
 

 105. 

Find the amount of work done when a 60 lb weight is moved 5 ft.
 

 106. 

A wheel diameter is 1 ft and a force of 60 lbs is applied.  What is your torque?
 
 
Terri is going to lift an engine block off the floor using a block and tackle.  She puts in 1,200 ft·lb of work.  The 600 lb engine block is raised 1.8 ft.
 

 107. 

Use pr107-1.jpg to calculate output work.
 

 108. 

Use % eff = pr108-1.jpg to find percentage efficiency.
 

 109. 

A weight lifter raises a 100 N barbell a distance of 3 m.  Calculate the work done by the weight lifter.
 

 110. 

A weight lifter is pushing on a wall with a force of 100 N.  But as hard as the weight lifter pushes, the wall doesn’t move.  How much work has the weight lifter done on the wall?
 

 111. 

Work = Force pr111-1.jpg Distance.  How much work is done if a dog pulls a sled (100 lbs) a distance of 60 feet?
 

 112. 

If a winch has a torque of 10 N·m applied through an angle of 180°, what is the input work?  If the winch is lifting a 3 kg mass 1 meter, what is the output work?  What is the efficiency of the winch?
 

 113. 

A hydraulic cylinder moves a piston 25 cm while applying a constant force to a load.  The pressure of the oil within the cylinder is 50,000 N/mpr113-1.jpg.  The face of the piston has an area of 3.5 cmpr113-2.jpg.  What work is done by the cylinder in making this move?
 

 114. 

In order for a room to have proper ventilation, a fan is used to move fresh air into a room—forcing the stale room air to the out-of-doors.  Each hour the fan causes a complete change of the room air.  The fan provides a force of 20 lb/ftpr114-1.jpg.  For a room having dimensions of 30 ft pr114-2.jpg 12 ft pr114-3.jpg 10 ft, what work will be done each hour by the fan?
 

 115. 

How much work must a water pump do to fill a 100 cubic foot tank that is 75 feet above a lake?
 
 
A hydraulic cylinder moves a piston 0.12 m while pushing a mechanical load.  The fluid pressure on the piston face is 4000 N/m2.  The area of the piston face is 0.0012 m2.
 

 116. 

Find the volume (DV) and convert V = AL.
 

 117. 

Use the formula pr117-1.jpg to calculate the work done to displace 0.05 m3 of fluid in a hydraulic jack under a constant pressure of 50,000 N/m2.
 

 118. 

When you blow out a candle, you blow 0.001 m3 of air under a pressure of 1,000 N/m2.  How much work did you do on the air?  (Use pr118-1.jpg.)
 

 119. 

One hundred pounds is to be lifted by a cylinder of diameter 1.5 inches.  What pressure must be applied into the cylinder?
 

 120. 

What is the pressure exerted by a 40 N force on a piston that has a diameter of 4 cm? 
(Hint: pr120-1.jpg and pr120-2.jpg.)
 

 121. 

If a current of 1 amp flows for 60 seconds, how much charge has moved by? 
Use pr121-1.jpg.
 

 122. 

What is the efficiency of a machine that has a work input of 4200 J and a work output of 3800 J?
 

 123. 

In pumping water, an electrical pump consumes 4500 J of energy while doing 3500 J of work.  What is the efficiency of the pump?
 

 124. 

A typical flashlight “D” cell can move about 3 coulombs of charge using 1.5 volts.  How many joules of work can the battery do?
 

 125. 

How much work does a heating element on a stove top do in 1 second if the voltage is 220 volts and the current is 10 amps?
 

 126. 

After touching down on a runway, an airplane is brought to a stop in 15 seconds.  If the acceleration of the plane was a constant -4.5 m/s2, what was the speed of the plane at touchdown?
 

 127. 

Determine the angular speed of the second hand of a clock in rad/s.
 

 128. 

A car is being driven at a constant speed along a street when the driver of the car decides to speed up in order to pass another car.  Find the acceleration of the wheels in rad/s2 if the wheel rotation increases from 5.5 rev/s to 8.8 rev/s in a time of 7.2 s.
 

 129. 

You traveled 400 miles in 8 hours.  What is your average velocity?
 

 130. 

A car traveling at 29.4 ft/sec increases its speed to 88.1 ft/sec in 5 seconds.  Find its acceleration.
 

 131. 

A car travels 100 miles in two hours, what is its average speed?  (pr131-1.jpg)
 

 132. 

A pilot increases the speed of an aircraft from 0 mi/hr to 200 mi/hr in 10 minutes.  What is the acceleration in mi/hr?
 

 133. 

Find the speed of a car that covers a 120-mile distance in 2 hours.  Remember to use proper labels.
 

 134. 

A car accelerates from stop to 10m/sec in 2 sec.  What’s the car’s acceleration? 
Use pr134-1.jpg.
 

 135. 

An automobile flywheel is rotating at 1000 rpm.  What’s its rate of rotation in rad/sec?
 

 136. 

If a car travels 120 miles in 2 hours at 60 mph, which variables represent the rate the car travels?
 

 137. 

If it takes 6 minutes to fill a 30-gal aquarium what is the flow rate?  Use pr137-1.jpg.
 

 138. 

Find the mass-flow rate of a liquid that has a weight of 1800 lbs and fills in 30 sec?
 

 139. 

You have 60,000 m3 of oil that is moved using a hose with a Qv rate of 400 m3/min.  How long will it take to move the oil?
 

 140. 

500 kg of air is circulated through a room by an air conditioner in 10 minutes.  What is the mass-flow rate of the air-conditioner?
 

 141. 

A tank holds 100 gallons of gasoline.  It takes 10 minutes to pump the tank dry.  Determine the volume flow rate.
 

 142. 

150 kg of ammonia gas flows through the cooling coils of a refrigerated truck in 3 minutes.  Find the mass flow rate of the gas.
 

 143. 

A tank holds 5000 gallons of water.  It can be filled in 2.5 hours.  What is the volume-flow rate of water through the pipe in gallons per minute?
 

 144. 

The tank on a firetruck holds 2500 gallons of water.  What must be the pumping rate, in gal/s, if this water is to maintain a steady stream for 3 minutes?
 

 145. 

If the pump that unloads an oil supertanker can pump 48,000 gallons of crude oil in one hour, what is the pump’s volume-flow rate in gal/min?
 

 146. 

If a 144,000 gallon swimming pool empties at the rate of 25 gallons per minute, how long will it take for the pool to empty?
 

 147. 

The calibration equation for an orifice flow plate is: pr147-1.jpg.  The flow rate, Qv, has units of gallons/min, and Dp has units of inches of water pressure.  What should the Dp be to have a flow-rate of 1000 gallons/min?  (Hint: to solve for Dp, square both sides of the equation first.)
 

 148. 

A pipe has a radius of 5 centimeters and is 50 centimeters long.  A float takes 10 seconds to cover the 50-centimeter distance.  The water has a depth of 5 centimeters in the pipe.  What is the rate of flow of water in the pipe in  cm3/sec? 

The following formulas will be helpful:
area of a circle = pr148-1.jpg
volume = pr148-2.jpg
pr148-3.jpg
 



 
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