WORK, POWER and ENERGY Explaining the causes of Motion without NEWTON

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Chapter 6

• WORK, POWER and ENERGY Explaining the causes of
  Motion without NEWTON

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Work

• The product of force and the amount of
  displacement in the direction of that applied
  force.
• The means by which energy is transferred from one
  object or system to another.
• Work (U) F x (d)
• Measured in Nm or joules

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Work - Continued

• To determine work
• What is the average force exerted on an object?
• What is the direction of the applied force?
• What is the displacement of the object along the
  line of action of the applied force during the
  time the force acts on the object.
• Work Examples

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Work-Continued

• Positive Work
• Negative Work

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Energy

• The capacity to do work.
• Kinetic Energy
• Potential Energy

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Kinetic Energy

• A moving object has the capacity to do work due
  to its motion. (book example)
• KE ½ m x v 2

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Potential Energy

• The energy a body has due to its position.
• 2 types
• Gravitational Potential
• Strain Energy

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Gravitational Potential

• PE W x H or M x g x h

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Strain Energy

• SE ½ k x change in x2

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Work Energy Relationship

• How are work and energy related?
• EXAMPLE Page 120

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Work - Energy

• Doing work to increase Energy-
• Doing work to decrease or absorb Energy-

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Conservation of Mechanical Energy

• The total mechanical energy of an object is
  constant if no external forces other than gravity
  act on the object.

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Power

• P F x v (How quickly or slowly work is done)