8.3. Simple Machines http://www.ck12.org
8.3 Simple Machines
- Name the simple machines.
- Define ideal mechanical advantage.
- Define actual mechanical advantage.
- Calculate both ideal and actual mechanical advantages for simple machines.
- Of the four variables, input force, output force, input distance, output distance, given three of them, calculate
the fourth for simple machines.
A "Rube Goldberg Machine" is a complex construction of many simple machines connected end-to-end in order to
accomplish a particular activity. By design, Rube Goldberg Machines are far more intricate than necessary, and may
be quite entertaining. Although this kind of construction may be extremely inefficient, simple machines commonly
make work easier, and can be found all around us.
Machines
A machine is an object or mechanical device that receives an input amount of work and transfers the energy to an
output amount of work. For anideal machine ,the input work and output work are always the same. Remember that
work is force times distance; even though theworkinput and output are equal, the inputforcedoes not necessarily
equal the outputforce, nor does the inputdistancenecessarily equal the outputdistance.
Machines can be incredibly complex (think of robots or automobiles), or very simple, such as a can opener. Asimple
machineis a mechanical device that changes the magnitude or direction of the force. There are six simple machines
that were first identified by Renaissance scientists: lever, pulley, inclined plane, screw, wedge, and wheel and axle.
These six simple machines can be combined together to formcompound machines.
We use simple machines because they give us amechanical advantage. Mechanical advantage is a measurement
of the force amplification of a machine. In ideal machines, where there is no friction and the input work and output
work are the same,