Simple Machines & Mechanical Advantage – Vocabulary Review

Vocabulary flashcards covering key terms and concepts from the lecture on simple machines, including types of levers, mechanical advantage, and efficiency.

Simple Machine

Any of six basic devices—lever, wheel and axle, pulley, inclined plane, wedge, and screw—that change the magnitude, direction, or distance of a force.

Machine

A device that makes work easier by transferring force, changing its direction, increasing its magnitude, or increasing the distance or speed over which it acts.

Effort Force (Input Force)

The force you apply to a machine.

Load / Resistance Force (Output Force)

The force a machine exerts on an object to perform the desired task.

Fulcrum

The fixed pivot point about which a lever rotates.

Mechanical Advantage (MA)

The ratio of output force to input force (or output distance to input distance). MA = output / input.

Lever

A rigid bar that pivots around a fulcrum and has both an effort force and a load.

First-Class Lever

Lever in which the fulcrum lies between the effort and the load; changes the direction of the effort (e.g., crowbar, seesaw).

Second-Class Lever

Lever in which the load lies between the fulcrum and the effort; multiplies force without changing its direction (e.g., wheelbarrow).

Third-Class Lever

Lever in which the effort lies between the fulcrum and the load; multiplies speed and distance but not force (e.g., tweezers, shovel).

Effort Arm

The distance from the fulcrum to where the effort force is applied on a lever.

Resistance Arm

The distance from the fulcrum to the load on a lever.

Wheel and Axle

A simple machine consisting of a large wheel rigidly attached to a smaller axle so that both rotate together.

Pulley

A grooved wheel that turns on an axle and is used with a rope to change the direction or magnitude of a force.

Fixed Pulley

Pulley anchored in place; changes the direction of the effort but provides no mechanical advantage.

Moveable Pulley

Pulley that rises and falls with the load; provides mechanical advantage equal to the number of supporting rope segments, but does not change direction.

Compound Pulley (Block and Tackle)

Combination of fixed and moveable pulleys that increases mechanical advantage while also changing direction.

Inclined Plane

A flat, sloping surface that allows a load to be raised over a greater distance with less effort.

Wedge

A device made of one or two inclined planes used to separate or hold objects; converts force applied to its blunt end into forces perpendicular to its inclined surfaces.

Screw

An inclined plane wrapped around a cylinder; converts rotational force into linear motion and offers high mechanical advantage.

MA of Lever

Equal to output force ÷ input force, or resistance arm length ÷ effort arm length.

MA of Inclined Plane

Equal to the length of the slope divided by its vertical height.

MA of Moveable Pulley

Equal to the number of rope segments supporting the moveable pulley.

Work Input

The product of effort force and the distance over which that force is applied to a machine.

Work Output

The product of load force and the distance over which the load is moved by the machine.

Efficiency

The ratio of work output to work input, expressed as a percentage; always less than 100% due to friction.

Trade-Off in Simple Machines

A machine can increase either force or distance/speed, but not both simultaneously.

Circular Ramp Analogy

Visualization of a screw’s threads as an inclined plane wrapped around a cylinder.

Six Simple Machines

Lever, Wheel and Axle, Pulley, Inclined Plane, Wedge, Screw.

Input Distance vs. Output Distance

In distance-multiplying machines (e.g., third-class lever) the output distance is greater than input distance, while force is reduced.

100% Efficiency Impossible

All real machines lose some energy to friction, preventing perfect efficiency.

Resistance Moves Farther than Effort

Characteristic of third-class levers where speed and distance of the load increase at the cost of greater effort force.