Thermal Expansion of Stuff: Solids 
Thermal Expansion of Stuff: Solids
by Prof. Miller
Video Lecture 19 of 46
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Date Added: February 5, 2015

Lecture Description

Most of the stuff in Nature expands when heated. And we have some wonderful and exciting demonstrations of this. In some cases some enchanting questions arise

A. The classical ball-and-ring demonstration: We have a metal ring
- brass - and a metal sphere - also brass. At room temperature we show that the ball does not go through the ring. So we say the ring is too small OR the ball is too big! Now we heat the ring and presto - the ball now goes through. We say the ring got bigger OR the hole got bigger! We must UNDERSTAND exactly what is going on here!

B. We now have some metal plates - round ones - square ones -
rectangular ones - and in each is a hole - a tiny tiny hole in
some. Now we heat these plates uniformly - as we could do in
an oven - and we ask: What does the tiny hole do? There are
only three cases: The hole does nothing.
The hole gets smaller.
The hole gets bigger. And I leave it as an enchanting exercise for you all to contemplate! I might give a HINT: The ring which we first used in the ball-and-ring demonstration is really a plate with a big hole! Got it now?

C. We have a metal ring - no need to say EXACTLY CIRCULAR. And
this ring has a diameter of its own stuff. We now heat this ring uniformly - as in the oven of my stove. Question: does the ring preserve its circularity or does it warp? Good question! Suggestion!
Those of you who think one thing should try to convince those who
think another! This is real intellectual inquiry.

D. A bimetallic strip consists of two metals fixed to each other along
their length. We heat the strip. Let us say one metal is iron -
the other brass. We see the strip bend. Question: does it bend
toward the iron or toward the brass.
A question for mathematical proof: If both strips are of equal thickness d the straight bimetallic strip will bend into a circle

E. We have two rods - both look like glass. One - we say - IS
glass; the other is quartz. We heat these to red-hot in a flame.
NOTE: while heating we see a color in the flame. Color is a
thermometric process. Then we immerse them both in a beaker of
COLD water. The glass shatters. The quartz does not. The quartz
has a very small temperature coefficient of expansion.

F. We introduce an interesting question: Consider one rail of the RR
track between Los Angeles and San Francisco. Let it be 400 miles
long - in one continuous strip. No breaks. Let this rail suffer an
overall change in temperature of - say 25°C. QUESTION: How
much expansion does this 400-mile rail suffer? ANSWER: Nearly
600 feet! Hard to believe but easy to prove:

G. Why does popcorn pop? A kernel of un-popped corn looks dry -
lifeless - inert - dead! But it is not dry! and it is not dead!
When we heat it the very tiny - very minute - bit of water which
is in it EXPANDS enormously - some 1700 times! The forces are
staggering!

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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