Why are simple machines used

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Why are simple machines used?
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• Simple machines are used to make work moving an
  object a distance easier.

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Draw Label the 3 types of levers
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(No Transcript)
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Describe mechanical advantage
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• The ratio of output force to input force for a
  machine.
• Ratio of resistance force to effort force in a
  machine.
• The advantage created by a machine that enables
  people to do work while using less force.

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Why is the pulley considered a simple
machine? What changes can be made to the
pulley system to make work easier?
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• The pulley is considered a simple machine because
  it is designed to make work easier. Using a
  pulley would require less force to lift a heavy
  object. Adding a longer rope to the pulley could
  help make work easier.

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List the 6 types of simple machines
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• Lever
• Pulley
• Inclined plane
• Screw
• Wedge
• Wheel axle

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A construction worker tries to remove a nail from
a board using a hammer and a crowbar. The
construction worker is not able to pull a nail
out of a board using a hammer. When the worker
tries using a crowbar, the nail comes out
easily.Use what you know about the
relationship between work, force, and distance to
explain why it was easier to use the crowbar to
remove the nail.
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• The crowbar is easier because it is longer than
  the hammer. Because it is longer, the crowbar
  handle moves farther than the hammer. Because the
  crowbar pulls on the nail for a greater distance,
  it can do as much work using a smaller force.

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The drawing below shows a student using a
screwdriver to open a paint can. To
change the force to the lid of the paint can, the
student can reposition her hand. How does moving
her hand change the force applied to the lid?
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• The student can move her hand closer or further
  from the end of the screwdriver to increase or
  decrease the force applied to the lid.

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The drawing below shows a student using a
screwdriver to open a paint can.
Describe how she could do this to apply less
force to the screwdriver to remove the lid.
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• To apply less force to the screwdriver to remove
  the lid, she needs to move her hand to the end of
  the screwdriver's handle.

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The drawing below shows a student using a
screwdriver to open a paint can.
Explain clearly how moving her hand allows
her to change the force.
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• The mechanical advantage of a lever is dependent
  on the distance the force is applied from the
  pivot. The larger the distance, the smaller the
  force.