Transcript Energy and Power - Effingham County Schools

Power
An Introduction
Power
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Learning Standard
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ENGR-EP-1. Students will utilize the ideas of energy, work,
power, and force to explain how systems convert, control,
transmit, and/or store energy and power
Power
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Concepts
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Identify the difference between work and power
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Define power
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Identify the basic power systems
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List the elements of all power systems
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Define horsepower (hp)
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Recognize the various power components in electrical circuits
and fluid circuits
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Summarize the advantages and disadvantages of various forms
of power
Power
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Concepts
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Describe various forms of power for specific applications
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Diagram the basic power components in an electrical circuit and
fluid circuit
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Calculate the efficiency of power systems and conversion
devices
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Compute power and horsepower for various forms of power
Power
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Vocabulary
Power
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Power: Introduction
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Power is needed in our technological society. Without it, our
society would not exist
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Work vs. Power
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Work is the application of force that moves an object a certain
distance.
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Power is the rate at which work is performed or energy is
expended.
Power
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Power System
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When energy is harnessed, converted, transmitted, and
controlled to perform useful work, this is call a power system
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There are three types of power systems:
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Electrical Systems
Mechanical Systems
Fluid Systems
Power
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Electrical Systems
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Electrical systems are power systems that use electrical energy
to do work. The most common electrical power components
include switches which control the flow of electricity within the
system, fuses or circuit breakers for protecting the electrical
circuitry, wires for transmitting electricity, and loads for
utilizing the electricity.
Power
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Mechanical Systems
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Mechanical systems are power systems that use mechanical
energy to do work. Machines are devices used to manage
mechanical power
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Six simple machines are used to control and change mechanical
power
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The lever
The pulley
The wheel and axle
The inclined plane
The wedge
The screw
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Fluid Systems
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Fluid systems perform work using the energy created by liquids
and gases. Fluid power can accomplish the movement of very
heavy objects. Fluid power components consist of valves, hoses,
air compressors or hydraulic pumps, cylinders, and motors.
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Two types of fluid systems
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Pneumatic systems
Hydraulic systems
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Characteristics of Power Systems
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Power systems come in various sizes and perform a wide variety
of tasks. Power can be produced by three forms: electrical,
mechanical, or fluid. In any of these three forms, power is
comprised of two basic, measurable characteristics: effort and
rate
Power
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Effort
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Effort is the force behind movement in a power system
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In linear mechanical power, effort is usually known as force and
is usually measured in pounds. In rotary mechanical power, the
term for effort is torque. Torque is a twisting or turning force
and is measured in foot-pounds
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In fluid power, effort is referred to as pressure. It is usually
measured in pounds per square inch
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In electrical power, the effort behind the movement of electrons
is called voltage. It is usually measure in volts
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Rate
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Rate is the characteristic of power that expresses a certain
quantity per unit of time. Regardless of the unit of measure, all
rate characteristics include both a quantity and a time element.
As quantity increase over time, a greater amount of work can be
preformed
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In electrical power, the measurement for rate of flow is the
ampere
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In mechanical power, the measurement is either revolutions per
minute or feet per minute
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In fluid power, the most common measurement is gallons per
minute
Power
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Basic Elements of Power Systems
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Energy Source: Required for all power systems to function
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Conversion Method: Necessary to convert the energy so some
type of work is produced
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Transmission Path: Needed to move energy to the point where it
is supposed to produce work
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Storage Medium: Necessary when power must be stored for use
at a later point in time
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Protection Devices: Shields components in power circuitry from
excessive effort or rate of flow
Power
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Basic Elements of Power Systems
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Advantage-Gaining Devices: Modify the effort and rate
characteristics of power in order to achieve a goal
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Control System: Needed to control the power within the system
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Measuring Devices: Required in power systems and provide a
source of feedback to monitor how well the system is
functioning
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Load: Output, the final goal of the power system
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Calculations of Power Systems
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The power available in a system can be measured or calculated
for each form of power – electricity, fluidics, or mechanical
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The ability to measure power is important because it gives
feedback to the operator on how the system is functioning or the
cost at which the system is functioning
Power
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Work
W = Fd
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Work is the force times the distance through which the force
acts.
Power
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Work
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A rider in a canoe weighs 120 lbs. How much work is being
done, if the canoe is paddled 600 ft.?
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If 2000 lbs. have to be moved 30 ft., how much work has to be
done?
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On a recent adventure trip, Anita went rock-climbing. Anita was
able to steadily lift her 150 lbs. body 60.0 ft. How much work
did she do?
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Bart runs up a 6.0 ft. high flight of stairs at a constant speed. If
Bart's mass is 165 lbs., determine the work which he did.
Power
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Power
P = W/t
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Power is the amount of work performed over time.
Power
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Power
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If a crane operator is going to move a 1000 lb. barrel of nails up
40 ft. to a fourth story window in 30 seconds, how much power
is developed?
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A physics teacher owns a family of squirrels. The squirrels have
been trained to do push-ups in repetitive fashion. Being
connected to an electrical generator, their ongoing exercise is
used to help power the home. There are 23 squirrels in the
family and their average mass is 1.07 lbs. They do work on the
"up" part of the push-up, raising their body an average distance
of 5.0 inches. If the squirrels averages 71 push-ups per minute,
then determine the total amount of work done in one minute
and the power generated by their activity.
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Efficiency
Output
X 100
Input
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Efficiency is the relationship between input energy, or power,
and output energy, or power
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Efficiency
Output
X 100
Input
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Efficiency is the relationship between input energy, or power,
and output energy, or power
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Efficiency
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Input Voltage: 120V
Output Voltage: 240 V
Input Amperage: 20 A
Output Amperage: 8.7A
What is the efficiency of the electrical system?
Drive Gear Input: 20 ft.-lbs.
Input Torque 100 rpm
Drive Gear Output: 9.7 ft.-lbs.
Output Torque 200 rpm
What is the efficiency of the mechanical system?
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Horsepower
W
hp =
t x 33,000
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Horsepower is one standard measuring unit of power. The
energy needed to lift 33,000 lbs. 1 ft. in 1 min.
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Horsepower
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If 200 lbs. are lifted 165 ft. in 1 minute, how much horsepower is
developed?
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If 380 lbs. is moved 350 ft. in 1 minute, how much horsepower
is developed?
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Measurement Conversion
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Two measuring systems are used in the U.S., U.S. customary
and SI metric. It is important to know how to convert these
measurements from one system to another
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Measurement Conversion