Energy

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Unit 7

• Energy Work

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Energy

• Energy the ability to do work
• (the ability to cause a change)

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Mechanical Energy

• Two types of mechanical energy
• Potential Energy - energy of position
• Kinetic energy energy of motion

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Kinetic Energy

• Kinetic energy energy of motion

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Kinetic energy

• What if the mass is doubled?
• What happens to the kinetic energy if the
  velocity is doubled?

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Potential Energy

• Potential energy energy of position/location
• Chemical potential
• Elastic potential
• Gravitational potential
• Electric potential
• Nuclear potential

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Gravitational Potential Energy
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Gravitational Potential Energy

• What happens to the gravitational potential
  energy if the mass is doubled?
• What if the height is doubled?

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Conservation of Energy

• Law of Conservation of Energy
• Energy cannot be created or destroyed. It can
  be transformed from one form to another, but the
  total amount of energy never changes.

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Pendulum
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Starts out not moving
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Starts out not moving
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Total energy kinetic potential
Total energy of the pendulum is conserved
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Conservation of Energy

• Law of Conservation of Energy
• Energy cannot be created or destroyed. It can
  be transformed from one form to another, but the
  total amount of energy never changes.
• - What are some examples of transformation of
  energy?

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Different starting conditions

• What if I start the pendulum higher?

Before
Now
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Different starting conditions

• What if I start the pendulum higher?

Before
Now
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Different starting conditions

• What if I push the pendulum instead of just
  letting go of it?

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Different starting conditions

• What if I push the pendulum instead of just
  letting go of it?

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Rollercoaster
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What would the energy bar chart look like?
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What would the energy bar chart look like?
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What would the energy bar chart look like?
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When does a pendulum have the most Total Energy ?
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Energy

• Energy initial Energy final
• Scenario A boulder resting on a hilltop
• What kind of energy does the boulder have at the
  top of the hill?
• What will happen to that energy as the boulder
  rolls down the hill? Why?
• What kind of energy does the boulder have as it
  rolls down the hill?
• What will happen to this energy as the boulder
  rolls down the hill? Why?
• What would happen to the two types of energy
  mentioned if the hill on which the boulder sits
  was much taller?

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Work

• Two things must occur for work to be done.
• 1- a force must be applied
• 2- something must move as a result of that
  force
• Work force x distance
• Or Wfd unit Nm or J (joules)

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Power

• Power rate at which work is done.
• P W
• t
• (unit is 1 J/s OR 1 W (watts))
• (i.e. 40 W 40 J/s)
• 1 horsepower 746 Watts