Study Guide for Simple Machines

Work - Is done when a force causes an object to move in the direction of the force.

\
Simple Machine - make work easier; NOT LESS WORK

\
[[==Work = Force (N) x Distance (m)==[[

\
Example: You push a box with 8N of force and the box moves 6m. How much work is done?

\
8N x 6N = 48J of Work

\
Power is the rate at which work is done. The faster you complete work, the more power you are generating.

\
}}Power (watts) = Work (J) / Time (s)}}

\
Example: You sand a piece of wood doing 45J of work in 5 seconds. How much power did you generate?

\
45J / 5 s = 9 watts

\
Machine - a device that makes work easier by changing the size or direction of the force.

\
Work Input - the amount of work you put into the machine.

\
Work Output - the amount of work done by the machine.

\
{{WORK OUTPUT CAN NEVER BE GREATER THAN WORK INPUT (FRICTION CAUSES THIS).{{

\
Mechanical Advantage - the number of times the machine multiplies force.

\
Mechanical Advantage = output force (N) / input force (N)

\
[[Mechanical Efficiency - work output/work input x 100 (measured as percentage %)[[

\
\
TYPES OF MACHINES

\
1st Class Lever - the fulcrum is between the input force and output force.

\

\
\
\
\
\
2nd Class Lever - fulcrum at one end with input force at the other end and output force in between.

\
\

\
\
\
\
3rd Class Lever - the input force is between the fulcrum and the output force.

\

\
\
\
Pulleys - a simple machine that has a grooved wheel and a rope or cable.

\
Wheel and Axle - simple machine consisting of two circular objects of two different sizes.

\
Incline Plane - a simple machine that is a straight slanted surface (ramp).

\
Wedges - a pair of inclined planes that move. (knife/axe)

\
Screws - an inclined plane wrapped around a cylinder.

\
<<MECHANICAL ADVANTAGE FORMULAS<<

\
Lever: Distance from Input Force to Fulcrum/Distance from Output Force to Fulcrum.

\
Incline Plane: Length of ramp/ Height of ramp

\
Wheel and Axle: Radius of the wheel / Radius of the axle

\
Pulley: Count # of pulleys

\
Wedge: Length of the wedge / the thickest part of the wedge.

\
Compound Machine: two or more machines combined into one.

\
\
\
\