What is a simple machine?
A basic mechanical device used to apply force and make work easier by changing its magnitude or direction.
Name the six classical types of simple machines.
Lever, Inclined Plane, Wheel and Axle, Pulley, Screw, and Wedge.
What is the formula for Mechanical Advantage (MA)?
MA = Load ÷ Effort
What is the formula for Velocity Ratio (VR)?
VR = Distance moved by Effort ÷ Distance moved by Load
How do you calculate Efficiency (η)?
η = (MA ÷ VR) × 100%
What is the principle of a lever?
Effort × Effort Arm = Load × Load Arm
What are the three classes of levers?
First Class: Fulcrum in the middle
Second
Class: Load in the middle
Third Class: Effort in the
middle
Give an example of a First Class Lever.
Seesaw, crowbar, scissors.
Give an example of a Second Class Lever.
Wheelbarrow, nutcracker.
Give an example of a Third Class Lever.
Tongs, fishing rod, human arm.
What is an Inclined Plane?
A slanted surface used to raise or lower objects more easily.
Formula for VR of an Inclined Plane?
$$ V.R = \frac{1}{sinθ} $$
What is a Pulley?
A wheel on an axle used with a rope to lift loads or change force direction.
What is the MA of a pulley system?
For ideal pulleys: MA = Number of supporting ropes
What is a Wheel and Axle?
A circular object (wheel) attached to a central shaft (axle); rotating the wheel turns the axle, amplifying force.
Formula for VR of a gear wheels?
$$ V.R = \frac{\text{Number of teeth on driven wheel}}{\text{Number of teeth on driving wheel}} $$
What is the V.R for a wheel and axle?
\[ V.R = \frac{\text{Distance moved by Effort}}{\text{Distance moved by Load}} = \frac{2\pi R}{2\pi r} = \frac{R}{r} \]
What is the formula for V.R of a screw?
\[ V.R = \frac{2\pi R}{P} \]
What does 100% efficiency mean?
No energy is lost. MA = VR
Why are real machines less than 100% efficient?
Because of friction, deformation, or heat loss, so MA < VR
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