Concerning Falling Bodies & Projectiles
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### Lecture Description

In FREE SPACE - that is, where there is no opposition to motion - as in a vacuum -ALL BODIES near the Earth fall with the same acceleration. This is a consequence of Newton's Second Law explored in Program *3 where we learned that F = ma and W = mg. In FREE FALL a body starting at rest falls 16' in the first second; 48' in the second second; 80' in the third second. These distances are in the ratio of 1:3:5. The total distance fallen is 16' in the first second; 64' in the first two seconds; 144' in the first three seconds. These distances are in the ratio of 1:4:9 which is to say - in the ratio of n:2^:3 . These interesting things were first arrived at by Galileo. When a body has motions both vertical and horizon¬tal simultaneously these motions take place independent of each other.

A - We show the Classical Guinea and Feather Tube. With the tube highly evacuated - much of the air taken out - the light feather and the heavy coin would fall side by side.

B - We show a record of a freely-falling body - electrically recorded every 1/60 of a second. The dots on the tape show the facts enumerated above but on a smaller scale.

C - When a body A is allowed to fall vertically and another B is projected horizontally a wonderful thing is observed: Both hit the ground at the same time! The path of B is a parabola.

D - When a body is projected vertically upward from a car moving horizontally another enchanting thing is observed: The car catches the ball later on in its path. At the instant the ball is projected up it has two motions: a vertical one which is acted on by gravity as a freely falling body and a horizontal motion which remains unaltered.

E - THE MONKEY AND HUNTER DEMONSTRATION is filled with Drama. With the gun bore-sighted on the Monkey the Monkey drops from his place high up at the instant the projectile emerges from the muzzle. The Monkey is hit!

F - If an array of bodies - say billiard balls - is fixed to a string in a manner following the numbers of Galileo - that is in a ratio like 1:4:9 and the string is allowed to fall vertically - the impact of the balls on the floor below occurs in equal time intervals.

We show a photograph - a likeness - of Galileo whose DIALOGUES should be read by every student. In these we find Sagredo and Salviati and Simplicio engaged in heated but friendly discussion of many of the Events of Nature -especially those we are concerned with here.

### 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.