USPS 955 Exam Graded A+
1st class lever - Answer- fulcrum is located between the input and output forces
Torque - Answer- a force that causes rotation
2nd class lever - Answer- fulcrum at the end, load in the middle; wheel barrow, car-jack
3rd class lever - Answer- fulcrum at the end, effort in the middle; tweezers, baseball bat
gear - Answer- A wheel with equally sized and spaced teeth located on its
circumference
circumference - Answer- The distance around a circle
Ohm's law formula - Answer- V = IR
HMI (Human Machine Interface) - Answer- A PLC device that provides means of
automated systems and people's interaction with the PLC control system.
lever - Answer- Simple machine that provides a mechanical advantage in carrying loads
fulcrum - Answer- Hinge point for the lever
input force - Answer- The effort that converts into output force
output force - Answer- The output force carries the load in a lever
Gear Ratio Formula - Answer- Number of teeth in wheel 1/number of teeth in wheel 2 =
Velocity of wheel 2/velocity of wheel 1
Pulley - Answer- A simple machine that consists of a grooved wheel with a rope or
cable wrapped around it.
fixed pulley - Answer- A pulley that is attached to a structure
moveable pulley - Answer- A pully that is directly attached to the load. Provides a
mechanical advantage by dividing the weight between the part of the rope connected to
the ceiling and the part that is pulled.
Applied force formula - Answer- F=W/N (Number of ropes)
Length of rope pulled formula - Answer- L= vertical distance of the load lifted
(D)/Number of Load supporting ropes (N)
, spring - Answer- Object used to store mechanical energy
Hooke's Law Formula - Answer- F = kx (spring constant x extension)
Incline Plane - Answer- A flat supporting surface tilted on an angle, used to help raise or
lower a load with less work
wedge - Answer- A compound tool that is triangular in shape. Can be used to seperate
two objects or portions of an object, lift an object, or hold an object in place.
Screw - Answer- Converts rotational motion into linear motion and a torque to a linear
force.
centrifugal force - Answer- Outward force that draws a rotating body away from the
center of rotation. Opposite direction to the center of the circle
centripedal force - Answer- The inward force that makes bodies follow a curved path
and is the cause of circular motion. The direction will move toward the center of the
circle.
hydrostatic pressure - Answer- The pressure of water against the walls of its container.
electrical circuit - Answer- Contains a power supply that is connected to a load via
conductive wires
Electrical load - Answer- Any device that converts electrical energy into a different form
(e.g. light bulb produces light, heater converts it to heat)
Electrical current formula - Answer- I=q/t
I is the current (A which are amps)
q is the charge (C)
t is the time (s)
Voltage - Answer- The difference in electrical potential energy between two places in a
circuit.
electrical resistance - Answer- The opposition posed by a material or a device to the
flow of current
electrical power - Answer- Measured in watts, is the rate at which electric energy is
transferred by an electric circuit.
Electrical power formula - Answer- P=IV
P is the electric power, V is the potential difference, and I is the electric current.
1st class lever - Answer- fulcrum is located between the input and output forces
Torque - Answer- a force that causes rotation
2nd class lever - Answer- fulcrum at the end, load in the middle; wheel barrow, car-jack
3rd class lever - Answer- fulcrum at the end, effort in the middle; tweezers, baseball bat
gear - Answer- A wheel with equally sized and spaced teeth located on its
circumference
circumference - Answer- The distance around a circle
Ohm's law formula - Answer- V = IR
HMI (Human Machine Interface) - Answer- A PLC device that provides means of
automated systems and people's interaction with the PLC control system.
lever - Answer- Simple machine that provides a mechanical advantage in carrying loads
fulcrum - Answer- Hinge point for the lever
input force - Answer- The effort that converts into output force
output force - Answer- The output force carries the load in a lever
Gear Ratio Formula - Answer- Number of teeth in wheel 1/number of teeth in wheel 2 =
Velocity of wheel 2/velocity of wheel 1
Pulley - Answer- A simple machine that consists of a grooved wheel with a rope or
cable wrapped around it.
fixed pulley - Answer- A pulley that is attached to a structure
moveable pulley - Answer- A pully that is directly attached to the load. Provides a
mechanical advantage by dividing the weight between the part of the rope connected to
the ceiling and the part that is pulled.
Applied force formula - Answer- F=W/N (Number of ropes)
Length of rope pulled formula - Answer- L= vertical distance of the load lifted
(D)/Number of Load supporting ropes (N)
, spring - Answer- Object used to store mechanical energy
Hooke's Law Formula - Answer- F = kx (spring constant x extension)
Incline Plane - Answer- A flat supporting surface tilted on an angle, used to help raise or
lower a load with less work
wedge - Answer- A compound tool that is triangular in shape. Can be used to seperate
two objects or portions of an object, lift an object, or hold an object in place.
Screw - Answer- Converts rotational motion into linear motion and a torque to a linear
force.
centrifugal force - Answer- Outward force that draws a rotating body away from the
center of rotation. Opposite direction to the center of the circle
centripedal force - Answer- The inward force that makes bodies follow a curved path
and is the cause of circular motion. The direction will move toward the center of the
circle.
hydrostatic pressure - Answer- The pressure of water against the walls of its container.
electrical circuit - Answer- Contains a power supply that is connected to a load via
conductive wires
Electrical load - Answer- Any device that converts electrical energy into a different form
(e.g. light bulb produces light, heater converts it to heat)
Electrical current formula - Answer- I=q/t
I is the current (A which are amps)
q is the charge (C)
t is the time (s)
Voltage - Answer- The difference in electrical potential energy between two places in a
circuit.
electrical resistance - Answer- The opposition posed by a material or a device to the
flow of current
electrical power - Answer- Measured in watts, is the rate at which electric energy is
transferred by an electric circuit.
Electrical power formula - Answer- P=IV
P is the electric power, V is the potential difference, and I is the electric current.
