Chapter 13 Energy

1
Chapter 13 Energy Power

• How is energy important to us?

2
Energy

• The ability to do work or cause change is called
  energy.
• Works is the transfer of energy.
• Two types of energy
• Kinetic energy is energy of motion.
• Potential energy is energy of position or shape.

3
Kinetic Energy

• Kinetic energy mass x (velocity)2/2
• Doubling the mass, doubles the kinetic energy.
• Double the velocity, quadruple the kinetic energy.

4
Potential Energy

• Elastic potential energy is energy stored when an
  object is stretched or compressed.
• Gravitational potential energy is energy stored
  because of the height of the objects position.
• Gravitational potential energy weight x height.
• Energy is measured in units called Joules.

5
Forms of Energy

• Mechanical energy is the energy associated with
  the motion or position of an object.
• Thermal energy is the total energy of the
  particles in an object.
• Chemical energy is the potential energy stored in
  chemical bonds that hold chemical compounds
  together.

6
Forms of Energy

• Electrical energy is moving electric charges
  produce electricity and energy.
• Electromagnetic energy travels in waves and have
  both electrical magnetic properties.
• Nuclear energy is energy stored in the nucleus of
  an atom and is released during nuclear reactions.

7
In which units do we measure energy?

• gram
• joule
• kilogram
• Newton

8
When you wind up a rubber band on an airplane,
what type of energy does this represent?

• Chemical potential energy
• Elastic potential energy
• Gravitational potential energy
• Kinetic energy

9
Which type of energy travels in waves?

• Electrical
• Electromagnetic
• Mechanical
• Nuclear

10
Energy Conversion and Conservation

• A change from one form of energy to another is
  called energy conversion.
• Most forms of energy can be converted into any
  other form.
• What is the energy conversion of the flashlight
  in the diagram on the right?

11
Energy Conversion

• What is the energy conversion for the fan in the
  diagram on the right?

12
Conservation of Energy

• Law of conservation of energy states that when
  one form of energy is converted to another, no
  energy is destroyed in the process.
• According to the law of conservation of energy,
  energy cannot be created or destroyed.

13
Fossil Fuels

• Fossil fuels are formed from the burying of
  plants and animals.
• Include coal, petroleum and natural gas.
• Fossil fuels contain energy that came from the
  sun.
• Fossil fuels can be burned to release the
  potential chemical energy stored millions of
  years ago.

14
Power

• Power is the rate at which work is done or the
  amount of work done in a unit of time.
• Power is calculated by dividing the amount of
  work done by the amount of time taken to do work.
  
• Power work/time
• Power force x distance/time
• Power is measured in watts.

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Power (continue)

• Power is the rate at which energy is transferred
  form one object to another or converted from one
  form to another.
• One horsepower is equal to 746 watts.

16
Pendulum Lab

• Purpose The purpose of this lab is for the
  students to learn which factor affects the period
  of the swing of a pendulum.
• Materials
• 3 different weights
• meter stick
• string
• stopwatch
• ring stand

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Pendulum Lab

• Procedure
• Tie a weight to the end of a string.
• Attached the other end of the string to the ring
  stand.
• Pull the weight back a standard distance and
  release the weight.
• Time how long it takes for ten cycles of the
  pendulum. Enter this data on the data table.

18
Pendulum Lab

• Divide the time by ten to find the time for a
  single swing.
• Change the weight and repeat procedures 1-5.
• Change the weight and repeat procedures 1-5.
• Next change the length of the string and keep the
  weight the same. Repeat procedures 1-5.

19
Pendulum Lab

• Change the length of the string a second time and
  keep the weight the same. Repeat procedures 1-5.
• Change the angle of release. Repeat procedures
  1-5.
• Change the angle of release. Repeat procedures
  1-5.

20
Pendulum Lab

• Questions
• Make a drawing of the pendulum. Indicate on the
  diagram the positions of the maximum potential
  energy and the maximum kinetic energy.
• What were the variables in this experiment?
  Which was the manipulative variable and which was
  the responding variable?
• Explain how the Law of the Conservation of Energy
  is observed in this experiment.
• What forces act on the pendulum to stop its
  motion?

21
Pendulum Lab

• Look at the diagram on the right.

22
Formative Assessment Review

• What are the two types of energy?
• (kinetic and potential)
• Which type of energy is energy of motion?
• (kinetic)
• Which type of energy is stored energy?
• (potential)
• Which type of energy is stored in a stretched
  rubberband or compressed spring?
• (elastic potential energy)
• Which type of energy is stored because of the
  position of the object?
• (gravitational potential energy)

23
Formative Assessment Review

• What is the formula for calculating kinetic
  energy?
• (KEmv2/2)
• What is the formula for calculating gravitational
  potential energy?
• (GPEw x h or GPEm x g x h)
• Name six forms of energy.
• (mechanical, thermal, chemical, electrical,
  electromagnetic, nuclear)
• Which law states that energy is neither created
  or destroyed?
• (Law of Conservation of Energy)
• What is the formula for calculating Power?
• (Pw/t)

24
Formative Assessment Review

• What unit is power measured?
• (watt)
• What unit is work or energy measured?
• (joule)
• What do we call the ability to do work or cause
  change?
• (energy)
• What happens to kinetic energy if the mass is
  doubled?
• (doubles)
• What happens to kinetic energy if the velocity
  doubles?
• (quadruples)
• _______________ is the transfer of energy.
• (work)

25
Formative Assessment Review

• What is the numerical value of gravitational
  acceleration?
• (9.8 m/s2)
• What energy is associated with motion or
  position?
• (mechanical)
• What energy is associated with the total energy
  of the particles of an object?
• (thermal)
• What energy is associated with the potential
  energy stored in chemical bonds?
• (chemical)
• What energy is produced by moving electric
  charges?
• (electrical)

26
Formative Assessment Review

• What energy travels in waves?
• (electromagnetic)
• What energy is stored in the nucleus of an atom?
  
• (nuclear)
• What is it called when an energy form changes to
  another form of energy?
• (converstions)
• Who stated that energy can be created by
  destroying matter?
• (Einstein)
• How is energy released from fossil fuel?
• (burning)

27
Formative Assessment Review

• What energy is mechanical energy converted to by
  friction?
• (thermal)
• Name three fossil fuels.
• (coal, petroleum, natural gas)
• _______________ is the rate at which work is
  done.
• (power)
• How many watts are in one horsepower?
• (746)