Levers, Inclines Planes, Geared-wheels and Other Machines
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Video Lecture 15 of 46
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Date Added: February 5, 2015

### Lecture Description

All the machines in the whole world - however complicated - are made up of combinations of the so-called SIMPLE MACHINES: The lever - the wheel and axle - the pulley - the inclined plane - the wedge - the screw. These can be further reduced to TWO: The lever and the inclined plane. All about us there are abundant illustrations of these wonderful devices:

A - The ordinary fork-and-knife at dinner: The knife is a lever AND an inclined plane! Why? When held in the hand it is used as a lever; the edge is sharp - and this is an inclined plane! The tines of the fork are also sharpened which makes them inclined planes! OK?

B - The screw-driver is a lever: We grasp the handle and twist. The
lever-arm is the radius of the handle. So it is really a lever. And a bigger screw-driver provides a bigger lever-arm!

C - The screw-thread is an inclined plane: If we wrap an inclined plane around a cylinder we get a "threaded screw" .

D - Wrenches are levers and Stillson wrenches are useful in the opening of screw-1 ids on bottles.

E - The ordinary kitchen grater is an array of inclined planes. The sharpened edges make them so.

F - A railroad spike is an inclined plane. So is a pointed nail.

G - The ordinary claw-hammer is obviously a lever. We increase the
mechanical advantage by using a block under the head as we pull a nail. AND NOTE WELL: The nail gets hot when we drive it IN and when we pull it OUT.

H - The nutcracker is a lever. The broom is a -lever. Indeed - as we show -the broom can be used as a lever of two different classes.

I - Metal shears are both levers and inclined planes.

J - A metal file - and a lady's nail file - are inclined planes.

K - A meat grinder is a compound machine - it consists of a lever and a screw. And the screw is an inclined plane.
And so we find these commonplace things possessing abundant enchantment when we explore them more thoroughly.

L - PULLEYS: The mechanical advantage of a pulley system is often calculates by counting the number of ropes supporting the load. This MAY give the right answer but it is NOT a reliable method. The point I wish to make here is this: We can.sometimes get the right answer by physically wrong means! This is bad.

We conclude this series of 15 programs with some large-scale philosophy: My ambition is NOT TO TEACH PHYSICS in these lessons - NOT TO POSE EXERCISES - NOT TO GIVE A COURSE IN PHYSICS. My singular ambition is to point up the Beauty and Drama in these Things - to stir your Curiosity -to awaken your Imagination - TO SEE HOW NATURE BEHAVES. Having always a watchful eye to THINGS ALL AROUND US and INCESSANTLY ASKING QUESTIONS will give a Fullness to Life and become a Stirring Adventure.

### Course Description

Demonstrations in Physics was an educational science series produced in Australia by ABC Television in 1969. The series was hosted by American scientist Julius Sumner Miller, who demonstrated experiments involving various disciplines in the world of physics. The series was also released in the United States under the title Science Demonstrations.

This program was a series of 45 shows (approximately 15 minutes each) on various topics in physics, organized into 3 units: Mechanics; Heat and Temperature / Toys; and Waves and Sound / Electricity and Magnetism.

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