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Physics in Context - 2nd Edition

Chapter 5: Energy

cover of physics in context 2nd edition textbook

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Mechanical and Fluid I

and Fluid II



5.1  Energy in Mechanical and Fluid Systems I

Calculating the Moment of Inertia for Rotating Masses
This page presents a concise introduction and presentation of rotational inertia for masses of different shapes, including a reference table of formulas for common shapes.

Comparison of Linear and Rotational Formulas
This page summarizes and shows the helpful similarities between the formulas and symbols that define linear and rotational motions, energies, etc., including some advanced concepts applicable to future lessons.

Rotational Kinetic Energy and Angular Momentum
This site of lecture notes on rotational kinetic energy and angular momentum includes parallels between straight-line motion and rotational motion. It also includes an example problem comparing the two.

Energy Simulations
Starting with a simple one-dimensional vibrating mass, this series of simulations (click List or Next) allow you to control many parameters and explore the effects on the system energy values with various masses and springs. (Requires Java.)

Velocity, Acceleration, Projectile and Circular Motion
Interactive graphing of projectile motion, showing velocity, acceleration, and energy at all times.

This topic stresses mechanical energy, potential and kinetic, and describes conversion between types of energy (while conserving the total amount), units, and the special position of heat. Be sure to follow the link to the lesson supplements.

Potential Energy
This site has an interactive simulation on the potential and kinetic energy of dropped balls. It includes explanatory material as well.

5.2  Energy in Mechanical and Fluid Systems II

Potential and Kinetic Energy
Following a review of mechanical Work, this sequence of Physics Classroom lessons on this site address potential and kinetic energy, including practice problems.

Bernoulli Biography
A biography of Daniel Bernoulli

Bernoulli's Equation
This page from a site discussing the aerodynamics of bicycles covers Bernoulli's equation and examples.

Energy of Masses and Springs
This PhET applet simulates a real lab with hanging masses and springs. Explore the changing energy picture with different masses, springs, and even different gravities! (Requires Java.)

Skateboarder Energy
This PhET applet simulates a skateboarder in a half-pipe, or whatever shape you configure. Explore the changing energy picture with different tracks, skaters, starting positions, and so forth. (Requires Java.)

This page gives an exhaustive—somewhat advanced—treatment of springs: the forces, potential and kinetic energies, characteristics of oscillation, and more.

Bernoulli's Principle
Another site describing the relationship between Bernoulli's equation and flight

Determine the Spring Constant
This page describes a lab activity to experimentally determine the spring constant for an unknown spring.

5.3  Energy in Electrical Systems

A Look at Home Energy Use
This site takes a quick look via infographics at how energy use has evolved over the past 150 years, and the sources of that energy. See the source links (bottom of the page) for a wealth of additional info students can explore, discuss, and analyze related to energy use.

How Stuff Works: Capacitors
A introduction to capacitors—how they work and some historical background—including a helpful explanation of capacitance units of measure: the farad.

Michael Faraday Biography
A detailed biographical look at Michael Faraday, a British chemist and physicist who contributed significantly to the early study of electromagnetism and electrochemistry.

Michael Faraday (1791-1867)
This biography of Michael Faraday comes from the Royal Institution of Great Britain. It includes links to some related RIGB exhibits, as well as to some of Faraday's writings.

Joseph Henry Biography
This biographical summary of Joseph Henry details his important contributions to electromagnetism and inductance and early contributions to electric motors. The unit of measure we use today for inductance is named after him.

Joseph Henry Papers Project
This is the Joseph Henry Papers Project of the Smithsonian Institutional History Division. It includes selected papers of Joseph Henry and other links describing his wide-ranging contributions to science.

Heinrich Lenz Biography
This biographical summary for the man who contributed our first understanding of the conservation of energy in electrical and magnetic circuits, stated as Lenz's Law, and whose initial "L" was chosen as the symbol commonly used for inductors in a circuit.

Lenz's Law
This site includes a java applet demonstrating Lenz's law.

5.4  Energy in Thermal Systems

The Second Law of Thermodynamics
This applet demonstrates the second law of thermodynamics with a bouncing ball of variable hardness. The accompanying linked explanation is enlightening, but may be too advanced. (Requires Java.)

Laws of Thermodynamics
This applet demonstrates the first and second laws of thermodynamics, showing the transition over time for a hot-cold scenario to an equilibrium state. (Requires Java.)

Heat Engine
Forward and reverse heat engines and the first and second laws of thermodynamics

The Carnot Cycle and the Efficiency of Engines
This applet demonstrates the pressure-volume relationship of a Carnot engine. (Requires Java.)

The Carnot Engine
A flash animation showing the cycling of a Carnot engine.

Sadi Carnot
This biographical article summarizes the life of Carnot, who recognized that the hot and cold temperature extremes in steam engines controlled its efficiency.

Celsius, Kelvin, and Fahrenheit Temperature Scales
This site includes definitions of the three temperature scales, and formulas for converting between them.

Lord Kelvin Biography
This biographical summary of Lord Kelvin details his important contributions to thermodynamics, and laying of telegraph cables across the Atlantic Ocean.

How Refrigerators Work
How does a refrigerator work? Check it out at How Stuff Works.

A Simple Finite Entropy Example
Entropy applet example using pixels.

The Page of Entropies
A light-hearted discussion of entropy, spanning entropy in poker hands, a box of air, and even water.