Levers

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Levers

• 1st Class Levers
• 2nd Class Levers
• 3rd Class Levers

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What is a Lever?

• A lever is a simple machine that is used to lift
  things.
• It is made up of a bar (called the lever stick)
  and a support (called the fulcrum).

Lever Stick
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Everyday Examples of Levers

• See-Saw
• Nutcracker
• Wheelbarrow
• Broom
• Can you think of any more?

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Parts of a Lever

• There are different parts and sections of a
  lever.
• You have the fulcrum and lever stick.
• You also have a force side and a load side.
• The relationship between the position of the load
  side, fulcrum, and force side determines what
  class of lever it is.

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Classes of Levers

• There are three different classes of levers.
• 1st Class force side-fulcrum-load side
• 2nd Class force side-load side-fulcrum
• 3rd class load side-force side-fulcrum

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1st Class Lever

• Structure of the 1st Class Lever
• Force Side-Fulcrum-Load Side
• The see-saw is an example of a first class lever.
• The force needed to lift the load decreases when
  the fulcrum gets closer to the load side.

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2nd Class Lever

• Structure of a 2nd Class Lever
• Force Side-Load Side-Fulcrum
• The wheelbarrow and the nutcracker are examples
  of a 2nd class lever.
• Again, The force needed to lift the load
  decreases when the fulcrum gets closer to the
  load side.

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3rd Class Lever

• Structure of a third class lever
• Load SideForce SideFulcrum
• The broom is an example of a 3rd class lever.
• The load is the dirt or end of the broom, the
  force is your bottom arm, and the fulcrum is your
  top hand.

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What type of lever am I (1,2,or3)?
1st Class
3rd Class
3rd Class
1st Class
3rd Class
2nd Class
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Wheels and Axles

• Wheel and Axle

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What is a Wheel Axle?

• A wheel and axle is a simple machine consisting
  of a wheel that revolves (turns) around a post
  (axle).
• This simple machine makes it easier for us to
  move things from one place to another.
• The further the force is away from the axle, the
  easier it is to turn the wheel. This means that
  it is easier to turn a big wheel than a small
  wheel.

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Pictures of Wheels and Axles
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Common Examples
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Pulleys

• Fixed Pulley
• Movable Pulley
• Block and Tackle

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What is a Pulley?

• Pulleys are a kind of simple machine that
  consists of a rope that fits onto a wheel and
  changes the direction of a force.
• There are three kinds of pulleys.
• Fixed Pulley
• Movable Pulley
• Block and Tackle (combo of fixed and movable)

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Fixed Pulley

• Wheel attached to surface
• Changes the direction of the applied force
• NO mechanical advantage same amount of force is
  required

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Movable Pulley

• Pulley moves along the rope
• Wheel supports the load
• Effort is in the same direction as movement
• Reduces the forces needed to move an object

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Block and Tackle

• Has at least two wheels (one movable and one
  fixed)
• The more complex the pulley, the more the effort
  needed to move the object decreases

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Common Examples Of Pulleys