Simple Machines

Six Types of Machines -- Inclined plane -- Wedge -- Lever -- Wheel and Axle -- Screw -- Pulley A simple machine does work by changing the amount or direction of the force needed to apply. It can also increase the distance of the output force.

Inclined Plane Friction decreases Flat, slanted efficiency surface Force is exerted over a longer distance Input force is less than output force Friction decreases efficiency The longer the inclined plane, the less input force is needed to make a push or pull

Wedge Like two inclined planes together that can move The longer Device that is thick at one end & tapers to a thin edge at the other The longer and thinner a wedge, the less input force needed Like two inclined planes together that can move wedge insert itself into Input force something makes the

Lever Fixed point in lever is 3 Advant-ages called fulcrum FULCRUM around a that pivots Rigid bar Fixed point in lever is called fulcrum 3 Advant-ages In center of Fulcrums do have to be lever NOT Changes direction, decreases force OR increases distance

First Class Lever

Second Class Lever

Third Class Lever

Screws Inclined plane wrapped around a cylinder Spiral inclined plane forms the threads of the screw Closer the threads are, the greater the mechanical advantage Increased distance results in increased output force

Checkpoints How are wedges and screws related? Why does a lid that requires eight twists to seal a jar require less input force than a similar lid that requires four twists?

Wheel and Axle Two circular or cylindrical objects that are fastened together and that rotate about a common axis In a screwdriver handle is the wheel and the shaft is the axle Doorknob – knob is the wheels and shaft is the axle The larger the circumference of the wheel, the less input force you have to do

Pulley Grooved wheels with a rope wrapped around it When you pull on the rope, you use the pulley Fixed pulley – attached to a structure; used to raise a sail (changes direction only) Movable pulley – attach a pulley to the object you want to move (changes direction & decreases force) Pulley systems – Combination of fixed and movable pulley systems (changes direction & decreases force)

Complex Machines Machine that utilizes two or more simple machines Your Rube Goldberg inventions will be a complex machine made of 4 or more simple machines Pencil sharpener