Lab 3P. 1

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Springs and Levers

• Lab 3

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Types of Springs

• Compression
• Tension
• Torsion

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Forms of Springs and Applications

• Coil and bending bar
• Applications
• To return something to its original position
• To measure force
• To store energy (potential)

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Application
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Springs Examples

• Valve spring of a car engine
• Door return spring
• Weighing machines
• Spring-driven clocks, mouse traps

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Other Forms of Springs

• Rubber bands
• Bunjy cords
• Other elastic cords

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Spring Constant

• To hold a spring either stretched or compressed
  an amount X from its normal length requires a
  force that is directly proportional to X.
• F k x k spring constant.
• It is a measure of the stiffness of a particular
  spring.

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Levers Principle

• Effort x Distanceeffort load x Distanceload

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Levers Classification

• First class
• Second class
• Third class

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First-class Levers

• Fulcrum is placed between load and effort
• If fulcrum at center effort load
• If fulcrum is twice as far from the fulcrum to
  the load effort load/2
• Examples balance, nail extractor, hand cart,
  pliers, scissors

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First Class
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Second-class Levers

• Fulcrum at one end of the bar and load at the
  other end
• Magnifies force and reduces distance
• Examples wheel barrow, bottle opener, nutcrackers

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Second Class
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Third Class Levers

• Fulcrum at one end of the bar and load at the
  other end
• Magnifies distance but reduces force!
• Examples hammer, fishing rod, tweezers

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Third Class
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Questions ?