Simple Machines Overview

Simple Machines

• Lever: A rigid bar that rests on a pivot point (fulcrum). Applying force to one end creates a turning force (torque) at the fulcrum.
• Examples: Scissors, see-saw, crowbar.
• Wheel and Axle: A wheel that rotates around a central rod (axle). Applying force to the wheel causes the wheel and axle to rotate.
• Examples: Door knob, bicycle wheel.
• Pulley: A wheel with a groove that holds a rope or cable. Pulling on the rope causes the pulley to rotate, lifting the object attached to the other end.
• Examples: Lift hills.
• Inclined Plane: A flat surface at an angle. It makes it easier to move objects from a lower to a higher level.
• Examples: Ramps, stairs.
• Wedge: A sharp, triangular object used to split or separate objects.
• Examples: Knives, axes, doorstops.
• Screw: An inclined plane wrapped around a cylinder or cone. Used to hold things together or to lift heavy loads.
• Examples: Lightbulbs, jars, and drills.

Mechanical Advantage

• Mechanical Advantage: A machine increases the force applied to an object. When a machine turns a small input force into a larger output force, it gives a mechanical advantage.
• Formula: Mechanical Advantage = Output Force / Input Force.
• Example: Pulling a nail with a hammer. A small force on the hammer produces a much larger force on the nail.

Class 1 Levers

• Effort and load are on opposite sides of the fulcrum: Making the effort arm longer than the load arm make lifting easier.
• Examples: See-saw, crowbar, scissors

Class 2 Levers

• Fulcrum is between the effort and the load: Making the load arm shorter than the effort arm makes lifting easier.
• Examples: Wheelbarrow, nutcrackers.

Class 3 Levers

• Effort is between the fulcrum and load: Making the effort arm shorter than the load arm makes lifting easier to move quickly but gives less force.
• Examples: Fishing rod, tweezers.