The Physics of Toys: Mechanical 
The Physics of Toys: Mechanical
by Prof. Miller
Video Lecture 28 of 46
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Date Added: February 5, 2015

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 Index

  1. The Idea of the Center of Gravity
  2. Newton's First Law of Motion: Inertia
  3. Newton's Second Law of Motion: The Elevator Problem
  4. Newton's Third Law of Motion: Momentum
  5. Energy and Momentum
  6. Concerning Falling Bodies & Projectiles
  7. The Simple Pendulum and Other Oscillating Things
  8. Adventures with Bernoulli: Bernoulli's Principle
  9. Soap Bubbles and Soap Films
  10. Atmospheric Pressure
  11. Centrifugal Force and Other Strange Matters
  12. The Strange Behavior of Rolling Things
  13. Archimedes' Principle
  14. Pascal's Principle: The Properties of Liquids
  15. Levers, Inclines Planes, Geared-wheels and Other Machines
  16. The Ideas of Heat and Temperature
  17. Thermometric Properties and Processes
  18. How to Produce Heat Energy
  19. Thermal Expansion of Stuff: Solids
  20. Thermal Expansion of Stuff: Gases & Liquids
  21. The Strange Thermal Behavior of Ice and Water
  22. Heat Energy Transfer by Conduction
  23. Heat Energy Transfer by Convection
  24. Heat Energy Transfer by Radiation
  25. Evaporation, Boiling, Freezing: A Dramatic Adventure
  26. Miscellaneous Adventures in Heat
  27. The Drama in Real Cold Stuff: Liquid Nitrogen
  28. The Physics of Toys: Mechanical
  29. The Physics of Toys: Acoustic and Thermal
  30. Waves: Kinds of Properties
  31. Sound Waves: Sources of Sound & Pitch and Frequency
  32. Vibrating Bars and Strings: The Phenomenon of Beats
  33. Resonance: Forced Vibrations
  34. Sounding Pipes
  35. Vibrating Rods and Plates
  36. Miscellaneous Adventures in Sound
  37. Electrostatic Phenomena: Foundations of Electricity
  38. Electrostatic Toys, Part 1
  39. Electrostatic Toys, Part 2
  40. Adventures with Electric Charges
  41. Adventures in Magnetism
  42. Ways to "Produce" Electricity
  43. Properties and Effects of Electric Currents
  44. Adventures in Electromagnetism
  45. Further Adventures in Electromagnetism
  46. Miscellaneous and Wondrous Things in E&M

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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