simple machines

work

the amount of energy transferred by a force applied through a finite distance in the direction of the motion.

joule

units of work

rotational work

work done when spinning or rotating

power

the rate of doing work; the rate at which energy is transferred

watt

units of power

kilowatt

1000 watts

machine

a device for multiplying forces or simply changing the direction of the force; does not make work less

simple machine

a basic machine where we assume effort y is 100%, generally refers to the 3-6 machines identified as classical simple machines.

efficiency

ratio of useful work output to total work input; can never exceed 100%

mechanical advantage

ratio of output to input force.

lever

an arm that pivots or turns against the fulcrum

fulcrum

pivot point of a lever

effort

force applied to a lever

resistance

what a lever is trying to move; also called the load

first class lever

the fulcrum is located between the effort and the resistance

second class lever

the resistance is between the effort and the fulcrum

third class lever

the effort is between the load and the fulcrum

inclined plane

a stationary sloping surface used to raise heavy loads with less effort than lifting straight up

wheel and axle

a modified lever consisting of a wheel connected to a rigid pole

pulley

a grooved wheel that turns around an axle; changes the direction of the force

simple pulley

also called a fixed pulley because it does not move; gains nothing in force, distance, speed, but changes the direction of force

moveable pulley

free axle pulley, able to move while transferring a load. depending on the setup can cause reduction in effort force and increase in distance

compound pulley

a combination of fixed and movable pulley

mechanical advantage of a pulley system

number that tells us the ratio of the load to the effort in an ideal pulley system

wedge

really just an inclined plane or two inclined planes used to lift/hold an object or pry objects apart

screw

inclined plane wrapped around a cylinder. used for fastening and also adjusting

pitch

the distance between to connecting threads on bolts or screws. often given as threads per inch in the US. Given as actual pitch in metric bolts