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Video Lecture 8 of 46
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### Lecture Description

When a fluid - a gas or a liquid - flows in a conduit - a pipe - of uniform cross-section - the pressure in the pipe is so much and the velocity of flow is so much. If now the fluid encounters a constriction in the pipe - a narrow-ness - TWO REMARKABLE THINGS OCCUR:

The velocity is increased The pressure is diminished

These remarkable events tell us how an airplane can fly - how a bird can soar -how a chimney has a good draft - how a flag flutters and a thousand other things. We show an array of exciting DEMONSTRATIONS bearing out these matters.

A - Two heavy croquet balls hang side by side with a little gap between.

When a stream of air is blown between them they are PUSHED TOGETHER by the greater pressure on their outer sides.

B - When a stream of air is blown across the top of a "chimney" - a vertical glass tube - the reduction in pressure is felt in the chimney and the atmospheric pressure outside drives the "soot" - the puffed rice -up the chimney. This is the principle of the atomizer.

C - When a ball is lodged in a funnel and the air is driven stoutly into the

funnel the ball is NOT driven out! This appears quite illogical until we think of Bernoulli's Principle.

D - Using a large-scale atomizer tube we blow a stream of air across the top of the spout of a closed tin can. The reduction in pressure is felt in the can. The atmosphere crushes the can! Very very dramatic!

E - A ball is supported on a vertical stream of air. We say the air pushes up -the ball pushes down. Now we deliver the stream of air off the vertical. The ball does not fall down! The secret? The ball is given a spin. This gives rise to a diminution in pressure on the UPPER side of the ball where¬upon the atmosphere below holds up the ball! Wonderful!

F - This phenomenon is demonstrated with a Toy Car.

The Bernoulli Family has had no likeness in all of history. There were over 120 bearing this illustrious name - and all were uncommon men - nearly all geniuses!

In their youngest years they showed remarkable intellectual competence in every body of knowledge - .mathematics - science - languages - philosophy medicine. An incredible thing!

### 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.