-transform energy;
-transfer forces from one place to another;
-change the direction of a force;
-change the magnitude of a force; and/or
-increase or decrease the speed.
Class 1 lever can move a heavy load with a small force. In a class 1 lever, the fulcrum is between the load force and the effort force. A load force is the force exerted by the load and the effort foce is the force required to move the load. An example of a Class 1 lever is a screw driver being used to pry off a lid of a paint can.
Class 2 levers always move a large load using a small effort force. Unlike in Class 1 lever, here the fulcrum is at one end. The load acts between the effort and the fulcrum. A wheelbarrowis an example.
Class 3 levers always make things harder to life or move instead of easier. In a class 3 lever, the fulcrum is at one end and the effort is exerted between the load and the fulcrum. As a result, the load arm is always longer than the effort arm. A fishing rod and a racket are examples of Class 3 levers.
Mechanical Advantage
Usefulness of a mechanism can be expressed in quantitive terms. Mechanical advantage is the number of times by which a machine can increase or decrease the effort force.
Mechanical Advantage (MA)= load force(N)/effort force (N).
Newtons=N. Mechanical advantage has no units.
Mechanical Advantage and levers With levers, the mechanical advantage is affected by the distance of the point of application of the load and effort forces from the following equation.
MA= length of effort arm/length of load arm.
When the effort arm increases, the mechanical advantage increases, also as the length of the load arm decreases. You now have two ways to calculate mechanical advantage: use the measuered lengths of the arms of the lever or the measured magnitude of forces shown.
The answers will be equal.
Velocity Ratio
The load force moves farther than the effort force in the same length of time. The velocity ratio is the ratio of the two distances:
VR= distance effort force moves/ distance load force moves.
Percentage Efficiency You can calculate the efficiency of a mechanism by using the following ratio:
PE= (mechanical advantage/velocity ratio) x 100.
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