Levers and Mechanical Advantage

1. Lever Definition: A lever is a simple machine consisting of a bar that rotates around a fixed point called the fulcrum Example: A Hammer. When you pull down on the handle the claw end pulls up on the nail. Using a hammer to remove a nail changes both the direction and strength of the applied force.

4 Lever Components Fulcrum: the pivot point of the lever. Load: whatever the lever is lifting. Load Arm: the part of the lever that supports the load. Effort Arm: the part of the lever where the force (the effort) is applied. Effort Force Load Effort arm Load arm Fulcrum When you pull down on the handle the claw end pulls up on the nail. Using a hammer to remove a nail changes both the direction and strength of the applied force.

Levers Cont… The longer the effort arm the easier it is to lift the load. In other words the mechanical advantage of a lever is greater when the effort arm is longer. Effort Force Load Effort arm Load arm Fulcrum To calculate the mechanical advantage of a lever, simply divide the length of the effort arm by the length of the resistance arm.

3 Classes of Levers: First Class Lever: Fulcrum (pivot) between the load and effort. Second Class Lever: The load is between the fulcrum and the effort. Third Class Lever: The effort is between the fulcrum and the load. FLE 123

Mechanical Advantage Mechanical advantage: is something that tells us how much a machine helps with the task. It is useful to think about a machine in terms of the input force (the force you apply) and the output force (force which is applied to the task). When a machine takes a small input force and increases the magnitude of the output force, a mechanical advantage has been produced.

Calculating MA Mechanical advantage is the ratio of output force divided by input force. MA = output force/input force MA = output distance (length of Load arm)/Input distance (length of effort arm) Draw equation on board MA= output force/Input force

Practice Question If a machine increases an input force of 10 pounds to an output force of 100 pounds, the machine has a mechanical advantage (MA) of what???

Practice Question In this example of output force is equal to the input force. What is the MA?

Show work: Remember: Output OVER input for equation.

Lever Example Handout!!!!