The Simple Pendulum and Other Oscillating Things 
The Simple Pendulum and Other Oscillating Things
by Prof. Miller
Video Lecture 7 of 46
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Date Added: February 5, 2015

Lecture Description

We learn in the Physics books that the Period - the time for one complete round-trip - of a Simple Pendulum - is given by this mathematics:
T = 2piSqrt(L/g)
This means that the time of oscillation is governed by the squareroot of the length and by g - that is - where on the Earth or on the Moon - do we clock it. ANY body can oscillate as a pendulum - say a rod - and this we call a Physical Pendulum. Every Physical Pendulum has an Equivalent Simple Pendulum - that is, a simple pendulum which keeps in phase with the motion of the Physical Pendulum. A loaded spring also oscillates with a Period governed by how stiff the spring is and what the load on it is. Oscillating bodies can be coupled with other oscillating bodies - that is - connected with them.

A- We show three Simple Pendulums of lengths 10, 40, 90 cm. We clock equal numbers of oscillations. The times come out to be very interest¬ing! In the ratio of 1:2:3.

B - Since the "formula" for the period of a simple pendulum does NOT involve the mass of the bob we show several pendulums with bobs of different size and mass.
C - We show in turn - a prismatic rod; a hoop; a disk. These all execute oscillatory motion as physical pendulums., The rod has special enchant¬ing properties: It has the same period at a point 2/3 its length as it does at its very end! And this tells us why a bat stings the hand sometimes!

D - We show an array of loaded springs - alone and coupled. The period of a loaded spring is given mathematically by
T = 2piSqrt(M/k)
where M is the load on the spring and k is its modulus - that is - a number which tells us how stiff it is.
A special interesting problem arises: If a spring of length L has a modulus k - what is the modulus of half such a spring? It turns out to be 2k -which is very exciting to know.
The genius Robert Hooke - who was a contemporary of Isaac Newton - discovered the Law of the Spring. He wrote it as an anagram in this way:
ceiiinosssttuv
And why did he write it this way? Because he was afraid Newton would steal it! The anagram reads
Ut tensio sic vis As the extension so the force.

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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