Simple Machines

1
Simple Machines

• Decrease the amount of work needed to move an
  object

2
Ramp

• An inclined plane that is used to lift an object
• The steeper the incline, the more is needed to
  lift the object
• Example
• Stairs
• Ramp

3
Screw

• An inclined plane that is wrapped around a
  cylinder
• The steepness of the incline is called the pitch
• Examples
• Screw
• Bolt
• Steering wheel

4
Pulley

• This is a chain or rope that is run around a
  wheel

5
Wedge

• A wedge converts motion in one direction into a
  splitting motion that acts at right angles to the
  blade. Nearly all cutting machines use the wedge.
  A lifting machine may use a wedge to get under a
  load.

6
Wheel and Axle

• In this machine a wheel or spoke is locked to a
  central axle so that when one is turned the other
  must turn. A longer motion at the edge of the
  wheel is converted to a shorter more powerful
  motion at the axle. In reverse, a short powerful
  force at the axle will move the wheel's edge a
  greater distance.

7
Levers

• Three classes (1st, 2nd, and 3rd)
• Used to move objects
• Three parts to a lever
• Fulcrum pivot point of the lever
• Effort location of the force created by the
  person moving the object
• Resistance force created by the object that is
  being moved

8
1st class lever

• Fulcrum is located in the middle of the lever
• Resistance is at one end of the lever
• Effort is at the opposite end from the resistance
• Example
• see saw
• diving board

9
2nd class lever

• Pivot is at one end of the fulcrum
• Resistance is in the middle of the lever
• Effort is at the opposite end of the fulcrum
• Examples
• Wheel barrel, pry bar

10
3rd class lever

• Fulcrum is at one end of the lever
• Effort is in the middle of the lever
• Resistance is at the opposite end from the
  fulcrum
• Examples
• Fishing rod, broom

11
Mechanical Advantage

• A method (formula) for calculating how much work
  is saved by using a lever
• Written as a fraction
• Resistance distance
• Effort distance
• If result is less than one, it takes less work
  than lifting the object without the lever
• If result is one, then the work is the same
• If result is more than one, it is harder than
  lifting the object without the lever