The Physics of Toys: Mechanical
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### Lecture Description

Toys - they say - are for children! They are for child's play. But toys embrace a vast reservoir of PHYSICS. And since ENERGY may be characterized as mechanical or acoustic or thermal or electrostatic or magnetic and so on - I choose to distinguish toys in this same fashion -by the KIND OF ENERGY they incorporate. So it is my conviction that PHYSICS can be taught to children by looking circumspectly at how the thing works. As young Maxwell put it: "What's the go of it?"

A. Pluto on a String: A dog is pulled over the table top by a string
fixed to his nose and a weight over the edge of the table. The dog
"wobbles" on his legs toward the very edge of the table top. And
we expect him to fall over the edge. But he does not. WHY? Because a horizontal pull can produce a horizontal motion and a vertical pull has no component in the horizontal. Thus we encounter
VECTORS.

B. The Bernoulli Car: A spring-wound car has a chimney and a fan
inside. We store elastic energy in the wound-up spring. A ball
atop the chimney stays with the car as the car rolls on the table
top. AND - the ball stays aloft even with the chimney tilted
off the vertical. WHY? The answer lies in Bernoulli's Principle
- which tells us why an airplane can fly - why a bird can soar
- why a ball can be thrown in a curve - and a thousand such like matters.

C. A wound-up spring puts a propeller aloft. The blades of the propeller "grip" the air. The air is thus pushed down which is why
the mechanism goes up. And when it lights on the table top it
spins like a top.

D. A plastic gun and a pingpong ball lodged in it: We press a pingpong ball into the muzzle of a "gun". The air in the gun is compressed. We now squeeze the walls of the gun. Out pops the ball.
And we can explore range - height - angle of projection and
do the classic problem of Galileo: A target can be hit by two
routes - one as much greater than 45 as the other is smaller. All
with a toy!

E. The Monocyclist: A one-wheeled rider - a Monocyclist - is
placed atop a stretched string. He is very jjnstable. Why? First:
his center of gravity is high above his point of support. Second:
his moment of inertia is very small. . .meaning that he can readily
tip over. So what must we do? We put some long/arms into his
sides - at his shoulders - these long arms bearing heavy masses
on their remote ends - and we see at once two things: His center
of gravity is lowered below his point of support AND his moment of
inertia is increased many-fold. He can now ride gracefully back
and forth on the tight string.

F. The Jumping Dog: A plastic dog has a spring in his neck. We put
the nose of the dog in some sticky stuff - which holds his head
down. The spring SLOWLY loosens the nose from the mooring and
the impulsive force delivered to the neck lifts the dog into the air
whereupon he rotates about his center of gravity and lands on his
feet!

So we close this brief conversation on MECHANICAL TOYS by saying once again - we find here enchantment abundant and PHYSICS no end.

### 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.