Lever

Levers can be used to exert a large force over a small distance at one end by exerting only a small force (effort) over a greater distance at the other.

A lever is a simple machine that can be used to multiply force by placing a small force at the far end of a rigid beam balanced over a fulcrum. A lever's beam can be made of any material, but it must be strong enough to be able to resist loads at the fulcrum point.

Levers are classified into three classes, based on the distance between the load, the fulcrum, and the location of the force applied.

First class

In a first class lever, the fulcrum is located between the load and the effort. When the fulcrum is closer to the load, then less effort is needed to move the load

In first class levers, the fulcrum us located between the load and the applied force. The shorter the distance between the fulcrum and the load, the less force needs to be applied at the opposite end of the beam.

First class levers are best for lifting large loads with small applications of force.

Examples of first class levers include crowbars, car jacks, and teeter-totters.

Second class

In second class levers, the load is between the applied force and the fulcrum. If the load is closer to the fulcrum than it is to the applied force, then the force required to move the load is reduced. If the load is closer to the applied force than it is to the fulcrum, then the force required to move the load is increased..

In a second class lever, the load is located between the effort and the fulcrum. When the fulcrum is closer to the load, then less effort is needed to move the load

Examples of second class levers include the the dolly, wheelbarrow, and bottle opener.

Third class

In third class levers, the applied force is between the load and fulcrum. Third class levers are best at moving loads large distances or with precision.

In a third class lever, the effort is located between the load and the fulcrum. If the fulcrum is closer to the load, then less effort is needed to move the load

Example of third class levers include tongs, fishing rods, or a shovel.

Dependencies

• Simple Machines
  • Lever

See also

• Inclined Plane
• Pulley
• Screw
• Wedge
• Wheel and axle
• Simple Machines