Simple Machines


Definitions:

Machine- A device that makes work easier by changing the speed , direction, or
amount of a force.

Simple Machine- A device that performs work with only one movement. Simple
machines include lever, wheel and axle, inclined plane, screw, and wedge.

Ideal Mechanical Advantage (IMA)- A machine in which work in equals work out;
such a machine would be frictionless and a 100% efficient IMA= De/Dr

Actual Mechanical Advantage (AMA)- It is pretty much the opposite of IMA meaning
it is not 100% efficient and it has friction. AMA= Fr/Fe

Efficiency- The amount of work put into a machine compared to how much useful
work is put out by the machine; always between 0% and 100%.

Friction- The force that resist motion between two surfaces that are touching
each other.

What do we use machines for?

Machines are used for many things. Machines are used in everyday life
just to make things easier. You use many machines in a day that you might take
for granted. For example a simple ordinary broom is a machine. It is a form of
a lever. Our country or world would never be this evolved if it wasn\'t for
machine. Almost every thing we do has a machine involved. We use machines to
manufacture goods, for transportation, ect.

In the W=F*d equation the trade of between force and distance is as you
use a machine the force goes down and distance goes up. If there was no friction
they would be equal and trade.

There are six simple machines. They are a lever, pulleys, inclined plain,
wheel and axle, screw, and wedge. The lever is used very often an example of a
lever is a broom. Your hand is the fulcrum and when you sweep it is a lever. A
lever consist of a fulcrum, effort, and resistance. A pulley is used to lift or
pull objects with a advantage. To get a advantage it matters how many lines are
going to the load. For example if there is 3 lines to the load it is a 3/1
advantage. A inclined plain is used to lift an object easier but with more work.
Instead of lifting it straight up you push it a greater distance but with less
force. A screw is a inclined plain wrapped around a cylinder post. Its like a
ramp around the screw.

A wedge is a inclined plain with one or two sloping sides. Chisels,
knives, and ax blades are examples of wedges.

IMA is ideal mechanical advantage meaning a frictionless world with 100%
efficiency. It is saying that work in and work out are exactly the same. AMA is
Actual Mechanical advantage meaning there is friction in the machine and the
efficiency could range from 0% to 99%. The difference between the two is one
has friction and more efficient and the other isn\'t.

Machines can never be 100% efficient because of friction. In a Ideal
world there is no friction but we don\'t live in a ideal world. We have friction
and efficiency is not always high or low but it is never 100%.

Added discussion

Believe it or not your arm is a simple machine. Your arm is a form of
lever. The muscles and bones work together as levers. The two bones in your
forearm act as the bar of the lever. Your elbow is the fulcrum of your lever.
When you contract your biceps, this muscle exerts an effort force on the
forearm bones to pull upward. the entire forearm is the resistance force.

Category: Science