Work, Power, and Simple Machines Review

Vocabulary flashcards covering core definitions, units, types of simple machines, mechanical advantage principles, and formulas for work and power.

Work

The transfer of energy that occurs when a force is exerted and causes an object to move.

Power

The rate at which work is done.

Machine

A device that makes work easier.

Input Force

The force you exert on a machine.

Output Force

The force the machine exerts on an object.

Input Work

The input force multiplied by the input distance.

Output Work

The output force multiplied by the output distance.

Efficiency

A comparison of the input work to the output work of a machine.

Compound Machine

A combination of two or more simple machines.

Ideal Machine

A theoretical machine with $100\%$ efficiency.

Joule

The SI unit of measurement for work.

Fulcrum

The fixed point that a lever rotates or pivots around.

Newton

The SI unit of measurement for force.

Inclined Plane

A simple machine featuring a flat, sloped surface; an example includes a ramp.

Wedge

A simple machine that is thick at one end and tapers to a thin edge; examples include a doorstop, axe, knife, zipper, razor, and shovel.

Screw

An inclined plane wrapped around a central cylinder; examples include a bolt, wood screw, and light bulb.

Lever

A simple machine consisting of a rigid bar that rotates around a fulcrum; examples include a shovel, light switch, can opener, crowbar, and scissors.

Wheel and Axle

A simple machine made of two attached circular or cylindrical objects that rotate together; examples include a screwdriver, car wheel, doorknob, and roller skates.

Pulley

A simple machine consisting of a grooved wheel with a rope or cable wrapped around it; examples include an elevator, crane, flagpole, and well.

Increasing Pulley Mechanical Advantage

Achieved by increasing the number of sections of rope that support the object.

Increasing Wheel and Axle Mechanical Advantage

Achieved by increasing the radius of the wheel and decreasing the radius of the axle.

Work Formula

$$\text{Work} = \text{force} \times \text{distance}$$

Power Formula

$\text{Power} = \frac{\text{work}}{\text{time}}$ or $\text{Power} = \frac{\text{force} \times \text{distance}}{\text{time}}$

Mechanical Advantage Formula

$$\text{Mechanical Advantage} = \frac{\text{output force}}{\text{input force}}$$

Machine Efficiency Formula

$$\text{Efficiency} = \frac{\text{output work}}{\text{input work}} \times 100\%$$

Three Ways a Machine Makes Work Easier

1. Changing the size of the force\n2. Changing the distance over which the force is exerted\n3. Changing the direction of the force

Condition for Work

Work is only performed when an applied force causes an object to move in the direction of that force; holding an object completely still performs no work because nothing is moving.