Week 22 - Mechanical Advantage, Speed Ratio and Gears

1 Simple Machines

Lesson 4

Read pages 258 - 260 and 315 - 320

Lesson 4: Analyze Mechanical Devices - Simple Machines

We are all familiar with the use of machines in our daily life to make our work easier. Some of these machines are very simple in nature, but some of them are made of many parts. We will begin our study with the examination of the types of simple machines that we commonly use. Combinations of these simple machines working together in a system make more complex machines - the topic of the next lesson
In this section, we are going to take a look at 6 different simple machines.

In your study of the lever, you will have discovered that there are three types of levers - first class, second class and third class. The following video segment will help you to understand better how levers work. Pay particular attention to the position of the fulcrum, the load force and the effort force in each of the three classes of lever.



View this website on types of levers:

http://www.enchantedlearning.com/physics/machines/Levers.shtml


Conclusions: The inclined plane, the wedge and the screw all related to each other. Generally, the inclined plane allows you to lift heavy objects using a smaller force. The down side is that you must do it over a greater distance.
The wedge is really two inclined planes together and it's main function is to split an object apart.

The screw can be thought of as an inclined plane wrapped around a cylindrical core. It functions by a rotational motion.

Pulleys
Videos on pulleys:
Let us examine the function of a pulley. We will first look at a simple pulley. The main function of a single pulley is to change the direction of the effort force.

See what happens when a second pulley is added to the system.
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This site allows you to work with simple pulleys and pulley systems to alter the masses in the system to see what happens. Try it out!

http://www.phy.ntnu.edu.tw/java/wheelAxle/pulley.html 
If above applet does not play, please watch this video.

Exercise 2.1: Everyday Machines



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