
Lecture Description
When we roll things down an inclined plane we discover a strange business: The mass of the rolling body does not matter. What matters is how the mass is distributed. To explore these wonderful thing we roll disks and hoops and spheres - all sizes - all masses and very enchanting discoveries are made.
A - We first roll a solid disk and a hoop. They have the same diameter -
the same mass - the same weight. How do they roll? That is - do they roll together? Does the disk win? Does the hoop win? We discover that the disk beats the hoop.
B - Now we roll an array of disks and hoops. And what do we find? We find that ALL disks roll alike. We find that ALL hoops roll alike. AND - we find that every disk beats every hoop. Little disks - big disks - fat disks - skinny disks - ALL DISKS BEAT ALL HOOPS. Now -how can I say this? One cannot roll ALL the disks and all the hoops in the whole WoTId! ANSWER: The MATHEMATICS tells us all this in a jiffy:
FR = lot and Mgh = 1/2 MV + 1/2 \(n . So you see how very much a brief sentence in mathematics can tell us.
C - We further find that ALL SPHERES ROLL ALIKE. Little spheres - big spheres - tiny spheres - ALL SPHERES - roll alike. But they must be solid uniform spheres like steel balls.
D - Now the question: Suppose we roll disks and spheres and hoops? What now? And to sum up our wonderful discoveries we say:
1 - All disks roll alike
2 - All hoops roll alike
3 - All spheres roll alike
4 - All spheres beat all disks
5 - All disks beat all hoops.
This is really wonderful to know.
E - The bodies we have rolled are very special. They are uniform in their mass distribution. So - we ask: what happens if the bodies are "loaded"? And so we roll two disks - one loaded near the center - one loaded at the edge. The centrally-loaded one wins.
F - The Yo-Yo has interesting behavior. It is a disk with an axis and the cis* rolls down a string. The string is like an inclined plane which is vertical. The mathematics above tells us how it rolls.
G - If a wheel - a disk - a ring - rolls without slipping on a roadway a good question to ask is this: What is the path marked out - traced out -described - by a point on the edge of the rolling wheel? The answer is very dramatic. The curve is called a cycloid and it is a very pretty thing to study.
Course Index
- The Idea of the Center of Gravity
- Newton's First Law of Motion: Inertia
- Newton's Second Law of Motion: The Elevator Problem
- Newton's Third Law of Motion: Momentum
- Energy and Momentum
- Concerning Falling Bodies & Projectiles
- The Simple Pendulum and Other Oscillating Things
- Adventures with Bernoulli: Bernoulli's Principle
- Soap Bubbles and Soap Films
- Atmospheric Pressure
- Centrifugal Force and Other Strange Matters
- The Strange Behavior of Rolling Things
- Archimedes' Principle
- Pascal's Principle: The Properties of Liquids
- Levers, Inclines Planes, Geared-wheels and Other Machines
- The Ideas of Heat and Temperature
- Thermometric Properties and Processes
- How to Produce Heat Energy
- Thermal Expansion of Stuff: Solids
- Thermal Expansion of Stuff: Gases & Liquids
- The Strange Thermal Behavior of Ice and Water
- Heat Energy Transfer by Conduction
- Heat Energy Transfer by Convection
- Heat Energy Transfer by Radiation
- Evaporation, Boiling, Freezing: A Dramatic Adventure
- Miscellaneous Adventures in Heat
- The Drama in Real Cold Stuff: Liquid Nitrogen
- The Physics of Toys: Mechanical
- The Physics of Toys: Acoustic and Thermal
- Waves: Kinds of Properties
- Sound Waves: Sources of Sound & Pitch and Frequency
- Vibrating Bars and Strings: The Phenomenon of Beats
- Resonance: Forced Vibrations
- Sounding Pipes
- Vibrating Rods and Plates
- Miscellaneous Adventures in Sound
- Electrostatic Phenomena: Foundations of Electricity
- Electrostatic Toys, Part 1
- Electrostatic Toys, Part 2
- Adventures with Electric Charges
- Adventures in Magnetism
- Ways to "Produce" Electricity
- Properties and Effects of Electric Currents
- Adventures in Electromagnetism
- Further Adventures in Electromagnetism
- 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.