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In this section, we will understand the functions of machines and input and output forces.




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A machine is tool to make work easier such as, a car, screwdriver, and laundry washers and driers. There are 3 ways that machines make a task much easier for us.



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1. Increasing the amount of force you exert

2. Increasing the distance in which you exert your force

3. Changing the direction in which you exert your force


1.Increasing the force

Example: Lobster crackers, nutcrackers

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A shell cracker is a tool that increases the amount of force applied. These tools function well because the force applied to jaws that crack the object is greater than the force exerted on the handles. Yet, the work done to the jaws is equal to the work applied to press the handles together and the distance that you move the handles is greater than the distance of moving the jaws. You use less effort to the handles over a large distance but apply a great effort to the jaws over a smaller area. Therefore, it makes much easier to crack a shell than with your bare hands.




2.Increasing the distance

Example: Ramps, inclining planes

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Ramps make it easier by using less force to transport heavy items to a higher point than lifting the item straight up. Lifting the item requires a large force over a small distance or the height. This inclined plane is useful because the length of the ramp is greater than the height of the ramp. Therefore, the person doesn't have to use as much force as he would have to to lift it.



3. Changing the Direction

Example: Fixed pulleys(Flag pole, Well pulley system)



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Machines, like fixed pulleys, change the direction in which you exert your force. when you apply downward force to the fixed pulley system, an upward forces applied to the object being lifted.


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Two forces, Input and output forces, are always in a machine that is doing work. When a person applies a force on the machine, the machine applies a force on the object.

The force that is applied to the machine is Input Force or (F in) and the force that the machine exerts to the object is Output Force or (F out). Input force can also be called the effort force, and the output force is called the load force.


Example: Hammer

When using a hammer, the input force is the effort applied to swing the hammer down and the output force is the force of the hammer hitting the nail.


Key Definitions:external image olde-key-hi.png

Input force-force applied to a machine

Output force- force that a machine applies to an object

Work- the amount of effort spent when a force causes an object to move a distance

Machines- and mechanical system that reduces the force needed to accomplish work