Mechanical Advantage

 Mechanical Advantage: the ability for a machine to make a task easier by reducing the amount of force required

The ratio of the amount of force produced by a machine compared to the amount of force you apply  Input Work = the work you do on the machine  Output Work = the work the machine does on the load

 MA = Output Force (N) = Load Force (F1) Input Force (N) Effort Force (F2) 

Examples of mechanical advantage BLM 4-4

The Mechanical Advantage of using a lever

MA = Effort Arm LengthLoad Arm Length

The Mechanical Advantage for a RampMA = Length of Ramp

Height of Ramp

MA = 30 = 310

H = 10 m

L = 30 m

The Mechanical Advantage for a Wheel and AxleMA = Length (or radius) of the Effort

ArmLength (or radius) of the

Load Arm

MA = 1 = .176

Wheel

Axle

Load Arm6 cm

Effort Arm 1 cm

The Mechanical Advantage for a Gear WheelMA = Number of driving gear teeth

Number of driven gear teeth (load)

MA = 60 = 1.540

Driving Gear

Driven Gear

60 Teeth

40 Teeth

If Mechanical Advantage = 1

the machine has not increased or decreased the amount of force applied

May have changed direction of forceExamples: no machine, a fixed pulley, parallel gears, class 1 lever (Fulcrum in the middle)

If Mechanical Advantage < 1

This usually involves a machine that produces a speed advantage or a distance advantageExamples: class 1 lever (fulcrum far from load), bike, class 3 levers (golf clubs, baseball bats, hockey sticks)

If Mechanical Advantage > 1

Use of the machine decreases the amount of force required

A force advantage is gained at the expense of speed or distanceExamples: class 1 and 2 levers, reducing gears, a large axle turning a small wheel, an inclined plane