5-3 Simple Machines

Chapter 5 Section 3

Simple Machines

Inclined Plane An inclined plane is a flat, slanted surface  Allows you to exert your input force over a distance 



A d va n ta g e s o f a n In clin e d P la n e Length of

incline Ideal mechanical advantage

---------------------------incline IMA=

3m ----1m

= Height of

= 3

The longer the incline, the less input force you need t o push or

E fficie n cy o f a n In clin e d P la n e Efficiency is lost on an inclined plane due to friction Efficiency can be increased by reducing friction Using a dolly with wheels and rolling it up a plane would reduce friction

Wedge  Wedge-

a device that is thick at one end and tapers to a thin edge at the other end (axe)  The longer and thinner a wedge is, the less input force is required

Screws  Screws

can be thought of as inclined planes wrapped around a cylinder



LE V E R S Le ve r-

a rig id b a r th a t is fre e to p ivo t, o r ro ta te , a b o u t a fixe d p o in t Fu lcru m - th e fixe d p o in t th a t a le ve r p ivo ts a ro u n d O p e n in g a ca n o f p a in t In cre a se s th e e ffe ct o f th e in p u t fo rce

Different Types of Levers

Advantage of a Lever  The

ideal mechanical advantage of a lever is calculated by :

 

Distance from fulcrum to input force





-----------------------------------------------------------Distance from fulcrum to output force



Advantage of a Wheel and Axle

Wheel and axle is a simple machine made of two circular or cylindrical objects that are fastened together and that rotate about a common axis  Wheel and axle multiplies your force, but the force is exerted over a longer distance (circular)  Radius of wheel Ideal Mechanical Advantage = --------------------- Radius of axle 

Variation on the wheel and axle











Wheel and Axle



Input force applied to the axle rather than the wheel Input force exerted over a short distance while the output force is exerted over a long distance Input force applied to the axle multiplies distance Ideal mechanical advantage is less than 1

Pulley 





Pulley- a grooved wheel with a rope wrapped around it Fixed Pulleys- a pulley attached to a structure * does not change the amount of force you apply, only the direction of the force













Movable Pulleys- a pulley attached to the object you wish to move * Ideal Mechanical Advantage is 2 * Output force more than 2x that of the input force * Input and output force are in the same direction Pulley System- ideal mechanical advantage of a pulley system is equal to the number of sections of the rope that support the object

Compound Machines  Complex

machines consist of combinations of simple machines (2 or more)  Mechanical advantage of a complex machine is the product of the individual ideal mechanical advantages of the simple machines  Gears- system with toothed wheels that fit into one another  Pencil sharpener