USPS Exam 955
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1. Ohm's law formula V = IR
2. HMI (Human Machine Interface) A PLC device that provides means
of automated systems and peo-
ple's interaction with the PLC con-
trol system.
3. lever Simple machine that provides a
mechanical advantage in carrying
loads
4. fulcrum Hinge point for the lever
5. input force The effort that converts into output
force
6. output force The output force carries the load
in a lever
7. 1st class lever fulcrum is located between the in-
put and output forces
8. Torque a force that causes rotation
9. 2nd class lever fulcrum at the end, load in the
middle; wheel barrow, car-jack
10. 3rd class lever fulcrum at the end, effort in the
middle; tweezers, baseball bat
11. gear A wheel with equally sized and
spaced teeth located on its cir-
cumference
, USPS Exam 955
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12. circumference The distance around a circle
13. Gear Ratio Formula Number of teeth in wheel 1/num-
ber of teeth in wheel 2 = Velocity
of wheel 2/velocity of wheel 1
14. Pulley A simple machine that consists of
a grooved wheel with a rope or
cable wrapped around it.
15. fixed pulley A pulley that is attached to a struc-
ture
16. moveable pulley A pully that is directly attached to
the load. Provides a mechanical
advantage by dividing the weight
between the part of the rope con-
nected to the ceiling and the part
that is pulled.
17. Applied force formula F=W/N (Number of ropes)
18. Length of rope pulled formula L= vertical distance of the load lift-
ed (D)/Number of Load support-
ing ropes (N)
19. spring Object used to store mechanical
energy
20. Hooke's Law Formula F = kx (spring constant x exten-
sion)
21. Incline Plane
, USPS Exam 955
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A flat supporting surface tilted on
an angle, used to help raise or
lower a load with less work
22. wedge A compound tool that is triangular
in shape. Can be used to seper-
ate two objects or portions of an
object, lift an object, or hold an
object in place.
23. Screw Converts rotational motion into
linear motion and a torque to a
linear force.
24. centrifugal force Outward force that draws a rotat-
ing body away from the center of
rotation. Opposite direction to the
center of the circle
25. centripedal force The inward force that makes bod-
ies follow a curved path and is the
cause of circular motion. The di-
rection will move toward the cen-
ter of the circle.
26. hydrostatic pressure The pressure of water against the
walls of its container.
27. electrical circuit Contains a power supply that is
connected to a load via conductive
wires
28. Electrical load
, USPS Exam 955
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Any device that converts electrical
energy into a different form (e.g.
light bulb produces light, heater
converts it to heat)
29. Electrical current formula I=q/t
I is the current (A which are
amps)
q is the charge (C)
t is the time (s)
30. Voltage The difference in electrical poten-
tial energy between two places in
a circuit.
31. electrical resistance The opposition posed by a mater-
ial or a device to the flow of current
32. electrical power Measured in watts, is the rate
at which electric energy is trans-
ferred by an electric circuit.
33. Electrical power formula P=IV
P is the electric power, V is the
potential difference, and I is the
electric current.
34. Volt Unit of voltage, or electrical po-
tential. One volt is the energy of
one Joule that is consumed when
an electric charge of one coulomb
flows in the circuit. 1V = 1J / 1C
Study online at https://quizlet.com/_hllfdt
1. Ohm's law formula V = IR
2. HMI (Human Machine Interface) A PLC device that provides means
of automated systems and peo-
ple's interaction with the PLC con-
trol system.
3. lever Simple machine that provides a
mechanical advantage in carrying
loads
4. fulcrum Hinge point for the lever
5. input force The effort that converts into output
force
6. output force The output force carries the load
in a lever
7. 1st class lever fulcrum is located between the in-
put and output forces
8. Torque a force that causes rotation
9. 2nd class lever fulcrum at the end, load in the
middle; wheel barrow, car-jack
10. 3rd class lever fulcrum at the end, effort in the
middle; tweezers, baseball bat
11. gear A wheel with equally sized and
spaced teeth located on its cir-
cumference
, USPS Exam 955
Study online at https://quizlet.com/_hllfdt
12. circumference The distance around a circle
13. Gear Ratio Formula Number of teeth in wheel 1/num-
ber of teeth in wheel 2 = Velocity
of wheel 2/velocity of wheel 1
14. Pulley A simple machine that consists of
a grooved wheel with a rope or
cable wrapped around it.
15. fixed pulley A pulley that is attached to a struc-
ture
16. moveable pulley A pully that is directly attached to
the load. Provides a mechanical
advantage by dividing the weight
between the part of the rope con-
nected to the ceiling and the part
that is pulled.
17. Applied force formula F=W/N (Number of ropes)
18. Length of rope pulled formula L= vertical distance of the load lift-
ed (D)/Number of Load support-
ing ropes (N)
19. spring Object used to store mechanical
energy
20. Hooke's Law Formula F = kx (spring constant x exten-
sion)
21. Incline Plane
, USPS Exam 955
Study online at https://quizlet.com/_hllfdt
A flat supporting surface tilted on
an angle, used to help raise or
lower a load with less work
22. wedge A compound tool that is triangular
in shape. Can be used to seper-
ate two objects or portions of an
object, lift an object, or hold an
object in place.
23. Screw Converts rotational motion into
linear motion and a torque to a
linear force.
24. centrifugal force Outward force that draws a rotat-
ing body away from the center of
rotation. Opposite direction to the
center of the circle
25. centripedal force The inward force that makes bod-
ies follow a curved path and is the
cause of circular motion. The di-
rection will move toward the cen-
ter of the circle.
26. hydrostatic pressure The pressure of water against the
walls of its container.
27. electrical circuit Contains a power supply that is
connected to a load via conductive
wires
28. Electrical load
, USPS Exam 955
Study online at https://quizlet.com/_hllfdt
Any device that converts electrical
energy into a different form (e.g.
light bulb produces light, heater
converts it to heat)
29. Electrical current formula I=q/t
I is the current (A which are
amps)
q is the charge (C)
t is the time (s)
30. Voltage The difference in electrical poten-
tial energy between two places in
a circuit.
31. electrical resistance The opposition posed by a mater-
ial or a device to the flow of current
32. electrical power Measured in watts, is the rate
at which electric energy is trans-
ferred by an electric circuit.
33. Electrical power formula P=IV
P is the electric power, V is the
potential difference, and I is the
electric current.
34. Volt Unit of voltage, or electrical po-
tential. One volt is the energy of
one Joule that is consumed when
an electric charge of one coulomb
flows in the circuit. 1V = 1J / 1C
