Machine Review

Inclined Plane Effort Force Load Distance Load Force Effort Distance

Pulleys Effort Distance Load Distance Effort Force Load Force

Lever Effort Force Load Distance Load Force Fulcrum Effort Distance

Classes of Levers

Simple Machines Machines help us do work by decreasing the Effort Force and increasing the Effort Distance needed to do the work. Work done remains the SAME! We are lifting the same load the same distance! L.F. x L.D. ≈ E.F. x E.D.

Load Force & Load Distance Load Force: Force a machine exerts to lift a load. When lifted straight up, it is equal to the weight of the load. Load Distance: Distance a load moves when acted on by a load force.

Effort Force & Effort Distance Effort Force: Force exerted by a person (or motor) when using a machine to lift a load. Effort Distance: The distance over which the effort force acts in a simple machine.

Mechanical Advantage Ideal Mechanical Advantage = Effort Distance / Load Distance Actual Mechanical Advantage = Load Force / Effort Force

Mechanical Advantage A High Actual Mechanical Advantage means: Little effort force is needed to lift a larger load. A High Ideal Mechanical Advantage means: Larger Effort Distance is needed to lift the load the load distance.

Actual vs. Ideal Mech. Adv. Actual Mechanical Advantage tends to be less than Ideal Mechanical Advantage because of FRICTION!

Input Work and Output Work Output Work = Load Force x Load Distance – Define Output Work: Work done on the load by a simple machine. Input Work = Effort Force x Effort Distance – Define Input Work: Work done by the effort force in a simple machine.

Efficiency Efficiency = Output Work/Input Work x 100 A high Efficiency means: amount of output work is very close to amount of input work. REMEMBER: A machine could have a high mechanical advantage, but low efficiency – and vice versa.

Equations Work (N-m) = Force (N) x Distance (m) – Input work = effort force x effort distance – Output work = load force x load distance Power (W) = Work (N-m) / Time (s) Slope of an Incline = Rise / Run Ideal Mechanical Advantage = Effort Distance / Load Distance Actual Mechanical Advantage = Load Force / Effort Force Efficiency = Output Work / Input Work x 100