Download Work and Energy unit guide and objectives 2012

Intro to Physics
Work and Energy Unit
Chapter 9
Key Terms
Work—unit Joules
Law of Conservation of
Energy
Work-Energy Theorem
Mechanical vs. nonmechanical energy
Pendulum and Period
g-force
Efficiency
Total work input
Useful work output
Mechanical advantage
Idealized vs. Actual
Mechanical Advantage
Power—unit Watts
Equations
W= Fd
P = W/t
Dissipated Energy
Types of Potential
Energy
Gravitational PE
(GPE = mgh)
Chemical PE
Elastic PE
Centripetal force
Law of conservation of
energy
Simple Machines
Lever family
Inclined plane family
st nd
rd
Lever (1 ,2 and 3
Ramp
class)
Pulley (fixed and
Wedge
movable)
Wheel and axle
Screw
MA = din/dout or
Efficiency = AMA/IMA
MA = Fout/Fin
or UWO/TWI
Types of Energy Problems to Solve
1.
2.
3.
4.
5.
6.
7.
Energy
Total Mechanical
Energy equation
TME = KE + PE
Kinetic Energy
KE = ½ mv2
Types of Kinetic Energy
Work
Power
Total Mechanical Energy
Gravitational Potential Energy
Kinetic Energy
Efficiency
Mechanical Advantage
Work, Power and Energy
Learning Objectives
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17.
Define work and energy, and explain how they are related.
Describe how energy is stored, transferred and used.
Define total mechanical energy.
What is the law of conservation of energy and how does the total
mechanical energy equation illustrate the law of conservation of
energy?
Explain the difference between kinetic and potential energy.
Know the three examples of potential energy learned in chapter
9.4.
Give four forms of kinetic energy as learned in chapter 9.6.
Define dissipated energy and its role in energy transfer. What is
the difference between mechanical and non-mechanical energy?
How do friction, air resistance, sound and vibrations influence total
mechanical energy?
How does a hydroelectric power station illustrate the transfer of
energy?
How does the Work-Energy Theorem describe the relationship
between work and energy?
Solve problems using the work equation identify SI units for each.
Define power and solve problems using the power equation.
Solve problems using the gravitational potential energy and kinetic
energy equations.
Use a pendulum to explain how work is done and energy is
transferred.
How does string length on a pendulum affect the period of its
swing?
Explain the law of conservation of energy.
Explain…
a. Why does a ball eventually stop bouncing?
b. Why does a person on a swing eventually come to a stop?
c. How does a diver illustrate the law of conservation of energy?
d. How does a roller coaster illustrate the law of conservation of
energy?
e. How does a skier illustrate the law of conservation of energy?
Simple Machines, Mechanical Advantage and Efficiency
Learning Objectives
1. Identify input force, output force, input distance, output distance,
effort arm, and resistance arm.
2. Calculate the mechanical advantage of ramps, pulleys and levers.
3. Explain how a machine makes work easier.
4. Explain why a machine does not reduce the work done on an object.
5. Determine the mechanical advantage of a machine using the
mechanical advantage equations.
6. Determine the idealized mechanical advantage of a pulley system.
7. Explain the difference between useful work output and total work
input.
8. Calculate the efficiency of a machine knowing useful and non-useful
work and actual and ideal mechanical advantage.
9. Explain why a machine is not 100% efficient.
10. Know the two families of simple machines.
11. Explain the differences between the three classes of lever.
12. Explain the difference between a simple and a compound (or complex)
machine.
13. Understand that input is equivalent to effort, output is equivalent to
resistance.