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 a100% efficient
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 advanced if it wasn’t for machines. Almost everything we do has a machine involved. We use machines to manufacture goods, for transportation, etc.
In the W=F*d equation the trade-off 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 plane, 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 consists of a fulcrum, effort, and resistance. A pulley is used to lift or pull objects with an advantage.
To get an advantage it matters how many lines are going to the load. For example, if there are 3 lines to the load it is a 3/1 advantage. An inclined plane 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 an inclined plane wrapped around a cylinder post. It’s 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 an “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 an ideal world, there is no friction but we don’t live in an ideal world. We have friction and efficiency is not always high or low but it is never 100%.
