Published and Publicly Accessible

Title Post date
Wind Turbines - Betz Law Explained 7 years 18 weeks ago
Wind Turbines Keywords: kinetic energy, power, wind energy, wind turbines

Can wind turbines actually be used to harness a substantial amount of power?

The total energy available in wind and the power that can feasibly be extracted from it will be determined using the fundamentals of kinematics. Following, the limitations of location and machinery of wind turbines that restrict the amount of power that can be harnessed will be examined, before comparing the impact of wind energy with various other common sources of energy.

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7 years 19 weeks ago
Why can't you just turn a nuclear reactor off? Keywords: nuclear reactor, shutdown

When a nuclear reactor gets into trouble, what's wrong with hitting the off switch?

When a uranium nucleus fissions into two, the resulting nuclei are not stable; they continue to decay and generate heat long after the fission chain reaction has stopped.

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6 years 25 weeks ago
What is a millisievert? Keywords: dose, human health, ionizing radiation

One Sievert means exposure to enough high-energy electromagnetic radiation to deposit one joule of energy in one kilogram of living tissue. A millisievert is 1/1000 of a sievert. But how dangerous is it?

The measure of ionizing radiation dose, as is applicable to human health, is the Sievert (Sv). One Sv implies a health impact equivalent to one joule of X-rays being absorbed by each kg of living tissue. Activity, the mean number of decay events per second, is measured in Becquerels (Bq). Knowledge of the activity, mean energy release per event, and exposure time, allows to estimate the dose.

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6 years 26 weeks ago
What do I (we) do about my (our) carbon footprint? Keywords: Carbon footprint, reduction

A very frequent question asked by students after learning about climate change is "But what can I (we) do about it?". Here are some ideas, all of which have benefits in addition to reducing greenhouse gases, and so are worth considering even if you reject the idea of anthropogenic global warming completely.

Here is a set of suggestions for science students who wish to take action to reduce their own and their family's or community's carbon footprint. Most of the ideas are about education and attitude. We also list three achievable ways of reducing your annual emissions by least a tonne of carbon dioxide.

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5 years 43 weeks ago
Wave Power – A Simple Analysis Keywords: power, waves

Will wave power save us?

A look at the amount of power potentially available in water waves.

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7 years 17 weeks ago
Volcanoes Keywords: albedo, anthropogenic climate change, solar radiation, Stefan-Boltzmann law

Will the Icelandic volcano cool us off?

Using some straightforward physics to assess the possible impact of the Eyjafjallajökull eruption on the climate.

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7 years 19 weeks ago
Vision and Diffraction Keywords: angle of resolution, circular aperture, diffraction, Rayleigh's criterion, vision

Why can eagles see more clearly farther away than we can?

The pupil acts like an aperture which diffracts light. The effect of this for humans and birds of prey is explored.

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7 years 17 weeks ago
Using spreadsheets Keywords: absolute and relative cell references, chi-squared, Excel, formulas, graphing, model, OpenOffice Calc, simulating data, Solver, spreadsheets, trend line, uncertainties

Want a quick way to do calculations, simulate data and draw graphs? Here are some quck tips on using spreadsheets to do this!

In this activity, we will use an accepted physical model, that of an object falling in a vacuum, to create simulated data that could result from an experiment. We will then graph this data and fit a trend line to it.

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7 years 19 weeks ago
Useful Numbers Keywords: numbers, units, values

Wondering where we got our numbers from?  Check out this table!

A summary of numbers commonly used throughout the articles and where they came from. (e.g. energy content of fuels, solar power, greenhouse gasses etc.)

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7 years 18 weeks ago
Turn the Heat Off! Keywords: energy loss, heat loss, power

Do you save more energy by leaving the heat on at night or by turning it down and reheating the house the next day?

We examine the benefit of turning off the heat when you go out.

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7 years 18 weeks ago
True, False, or Not Sure? Philosophy of Science in the 21st century Keywords: nature of science, normal science, philosophy of science, post-normal science

Whatever happened to objective reality? Why is climate change so hard to prove?

A brief overview of normal and post-normal science.

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7 years 17 weeks ago
TriColour LED Flashlight Keywords: activity, battery, breadboard, circuit, colour addition, LED, resistors, switch, tricolour LED

Make your own TriColour LED Flashlight!

This is a straightforward classroom or summer camp activity to teach students simple circuitry and the addition of colours. The students can go home with a useful and energy-efficient flashlight.

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6 years 4 weeks ago
Trend Analysis in the Context of Global Warming Keywords: anthropogenic climate change, climate, climate change, trend analysis

There are many sources ranging from politicians to mass media that claim that the Earth is actually cooling, not warming as scientists say it is. Unusually cold periods and local changes in weather are generally the cause for these statements. Why are these claims inaccurate?

There are many claims made refuting the existence of global warming. Most of these claims come from looking at very short term data in a very localized region. Global warming, as the name implies, is an increase in the global temperature and conclusions about it cannot be reached using measurements localized in time and space. Doing so is called "cherry picking".

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2 years 7 weeks ago
Transmitting Electricity Keywords: power, resistance, resistivity, transformer, voltage

If high voltage is so dangerous, why do we transmit electricity that way?

Transmitting power at higher voltages ensures that power can be transmitted over long distances with minimal losses; if transferred at a low voltage, the transmission distance has to be greatly minimized, which is impractical.

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7 years 5 weeks ago
Transformers Keywords: transformer, voltage

Electrical energy is transmitted at high voltage. Which element creates the 120 V that is available in our wall plugs ant home?

Transformers operate on principles of electromagnetism to step up and step down voltages. This allows for efficient transmission of power across the grid to homes and buildings. It also ensures that the voltage from our sockets is appropriate for home and appliance use.

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7 years 4 weeks ago
Thermal Radiation Keywords: black body radiation, infrared, thermal radiation

All bodies emit radiation. So why don't we all shine in the dark?

Thermal radiation is a crucial part of our macro and micro environments. Although invisible to the eye it can be measured and imaged.

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7 years 14 weeks ago
Symbols and Units Used on this Site Keywords: symbols, units

Wondering what each symbol refers to?

A summary of symbols commonly used throughout the articles.

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7 years 16 weeks ago
Stretching Rubber Bands Keywords: Elasticity, Hooke's Law, Rubber bands, Young's Modulus

Why is this energy bar hanging from a rubber band?

In this project you will explore the elastic properties of rubber bands.

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4 years 28 weeks ago
Steam Burns Keywords: heat, heat of vaporization, phase changed, specific heat, temperature change

Why can steam at 100 degree celsius burn worse than boiling water at 100 degree celsius?

This article explains why steam at 100 degC transfers more thermal energy to your skin than an equivalent mass of boiling water at 100 degC.

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5 years 28 weeks ago
Solar Powered Airplanes Keywords: airplanes, estimation, solar cells, solar energy

If we were to coat a Boeing 747 jumbo jet with solar panels, is it possible to fly it using only the energy generated by these solar panels?

This module introduces the concept of estimation, both in the sense of rounding extremely precise numbers off to remove excessive significant figures, and simplifying a complex process (the flight of a 747) to a simpler one, by evaluating the possibility of powering a 747 with solar panels.

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7 years 17 weeks ago
Solar Energy: How do photovoltaics work? Keywords: photovoltaics, solar, solar panel

How does energy from the sun get transformed into electricity? Learn how photovoltaic panels work, converting light into electrical energy.

Learn how photovoltaic panels work, converting light into electrical energy.

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1 year 47 weeks ago
Solar Energy in a Temperate Climate. Keywords: photovoltaic cell, solar cells, solar energy, solar radiation

Does it pay to cover your roof with solar panels in Vancouver?

We show the example calculation of expected amount of energy, which can be obtained in Vancouver from a roof covered with solar cells.

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7 years 15 weeks ago
Simple Earth Climate Model: Single-Layer Imperfect Greenhouse Atmosphere Keywords: albedo, black body radiation, climate, conservation of energy, emissivity, energy balance, heat transfer, Stefan-Boltzmann law, surface temperature

Why does the emission of carbon dioxide influence our climate?

The article explains the connection between carbon dioxide and an increase in the average surface temperature on Earth.

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7 years 18 weeks ago
Simple Earth Climate Model - Single-Layer Perfect Greenhouse Atmosphere 7 years 18 weeks ago
Simple Earth Climate Model - Additional Concept Explanations 7 years 18 weeks ago
Simple Earth Climate Model Keywords: albedo, black body radiation, climate, conservation of energy, energy balance, heat transfer, Stefan-Boltzmann law, surface temperature

Which planetary characteristics contribute to producing a mean surface temperature that makes Earth habitable?

Developing a simple model of Earth's atmosphere to infer what physical processes are important in maintaining a mean global temperature of about 14.5°C. Further, the model can also be used to show how this temperature can change.

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7 years 18 weeks ago
Significant Figures Keywords: calculators, mathematics, physics, significant figures, what numbers mean

This tyrannosaurus is 70,000,003 years old. How many significant figures should I quote?

We examine this perennial student hang-up.

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7 years 14 weeks ago
Scientific Notation Keywords: scientific notation

The suspect is a male, age 1.73 × 109 s, height 1.83 m, weight 7.5 × 101 kg.

Understanding how to express numbers in a way that is easily understood.

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7 years 15 weeks ago
Renewable Energies Keywords: biofuel, electricity generation, energy, hydro-electricity, Renewable, solar energy, wind energy

Energy is always required, whether it be for the production of goods, the supplying of services, or for transportation. Can we reduce our emissions by turning to clean sources of energy? If so, why haven't we already?

A large portion of humanity's energy demands are met using fossil fuels. Switching from fossil fuel generation to cleaner sources could greatly reduce the carbon emission put out every year. There are many ways to obtain energy cleanly, each with their own advantages and challenges.

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2 years 7 weeks ago
Radioactive Milk Keywords: activity, dose, nucleosynthesis, Radioactivity

Milk contains enough radioactive potassium-40 to set a Geiger Counter humming. But it didn't come from Fukushima, or any human activity.

Milk (and own bones) contains a lot of ancient radioactive potassium-40, which was made in a supernova explosion about five billion years ago.

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6 years 24 weeks ago
Pitot Tubes Keywords: air speed, Bernoulli's equation, fluid speed, fluids, Pitot tubes

How can wasps endanger a commercial airline flight?

This article explains how a Pitot tube is used to measure speed of a fluid and is applied to measure the air speed of aircraft. Bernoulli's equation forms the basic principle of fluid speed measurements using Pitot tubes.

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3 years 12 weeks ago
Oscillations and Waves Keywords: Circular Motion, interference, Oscillations, Rotational Motion, Standing Waves, Superposition, waves

What do waves, oscillations, and rotations have in common?

Surprisingly, rotations, oscillations, and waves can be described with similar math. In this article, we make the math come alive by using Excel or Calc programs to simulate oscillations and wave effects. You can learn how to do this yourself by following our videos.

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4 years 35 weeks ago
Order of Magnitude Calculations Keywords: approximation, calculation, estimation, order of magnitude

How can we make reasonable approximations without tedious calculations?

Use order of magnitude calculations to make reasonable approximations.

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7 years 18 weeks ago
Oil Sands (a.k.a. Tar Sands) Keywords: fluid-particle physics, Oilsands, Stokes' Law

How do you separate bitumen from sand with the least energy cost?

Separating bitumen from sand involves the clever use of simple fluid physics.

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6 years 15 weeks ago
Nuclear Fission Project Keywords: chemical, nuclear, reaction rates

Yes, you can do this at home.

Students can model a self-sustaining reaction using ping pong balls and mouse traps while varying the density/concentration of the reactants to see how that affects the rate of reaction.

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5 years 24 weeks ago
Nuclear Energy Basics Keywords: energy, health, ionizing radiation, nuclear, power, safety

What is the physical basis of nuclear power? Is nuclear power good or bad for the environment, safe or dangerous for us?

A look at the energy in the nucleus of a uranium atom, how this can be used to provide a reliable source of energy, and impact of this on the environment.

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7 years 15 weeks ago
Nerve Impulses Keywords: nerve impulses, neurons, reaction time

How fast does a nerve signal travel?

This example takes typical eye-hand and eye-foot reaction times and calculates the average speed at which a signal travels along the nervous system. Why are eye-foot and eye-hand reaction times different?

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7 years 17 weeks ago
MRI Machines and You Keywords:

Quantum Mechanics + Radio Waves = Pictures of your Brain

An explanation of how MRI machines take advantage of nuclear spins to image precise slices of a person.

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4 years 32 weeks ago
Metabolism, Heat Loss, and Size Keywords: allometric relation, heat, heat loss, mass, metabolic rate, surface area, volume

The bigger the better?

Heat loss per unit gram is compared for large arnimals versus smaller animals.

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7 years 16 weeks ago
Man on a Missile Keywords: acceleration, force, g-force, Netwon's second law

How much force can the body withstand upon impact?

In this article we calculate the average force experienced by Colonel Stapp during one of his most famous experiments on deceleration.

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7 years 17 weeks ago
Low-E Glass Keywords: emissivity, thermal radiation

How do you tell the difference between low-E and regular glass?

With a cheap IR thermometer, low-E glass can be easily distinguished from the normal variety.

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5 years 1 week ago
Light-Emitting Diodes (LEDs) 7 years 15 weeks ago
Light Theremin (Simple) Keywords: Hands-Free, Light Theremin, Lights Sensing Instrument

Is it possible to create a musical instrument that can be played without direct contact?

This project takes the student through the steps to build a simple Light Theremin, an instrument which changes its pitch depending on how much light is shone upon it.

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4 years 3 weeks ago
Light Theremin (Advanced) Keywords: Generate Sine Wave, Light Sensing Instrument, Light Theremin

Is it possible to create a musical instrument that can be played without direct contact?

A more complicated version of the simple Light Theremin. This version uses another light sensor for volume control, and sounds much closer to the original Capacitive Theremin.

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4 years 3 weeks ago
Light Bulb Efficiency and Hand Crank Energy Generation Keywords: breadboard, circuit, efficiency, electricity generation, energy, energy conversion, Lend an Experiment (LEx), lighting

What does it really take to power a light bulb?

This activity is part of the LEx (Lend an Experiment) Climate Kit. Students compare the power consumption of incandescent and LED bulbs through the use of hand crank generators and a simple circuit. Concepts include the conversion of mechanical to electrical energy, power and efficiency, and measurement estimation. There is an option to also investigate the efficiency of the hand crank generator.

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2 years 1 day ago
LaTex Expressions - Symbols and Units Keywords: LaTeX, symbols, units

Wondering what each symbol refers to?

A summary of symbols commonly used throughout the articles and the corresponding LaTeX expressions.

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7 years 15 weeks ago
Laminar (Un)mixing Keywords: activity, fluids, laminar flow, mixing, reynolds number

"Unmixing" a mixture is impossible, right? So what's going on here?

Find out how to construct your own "(un)mixing" demonstration and learn about how it works here.

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4 years 39 weeks ago
Investigating the Greenhouse Effect and Passive Solar Heating Keywords: greenhouse effect, Lend an Experiment (LEx), thermal absorption

We all know a car sitting outside in the sun all day can get dangerously hot inside, but why? What does this have to do with the greenhouse effect?

This activity is part of the LEx (Lend an Experiment) Climate Kit. Students explore the way materials and surfaces interact with solar radiation. We introduce the idea of the greenhouse effect, and build a small model to illustrate how it works.

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1 year 49 weeks ago
Interference and Colour, Part II - Thin Film Interference Keywords: absorption, colour, diffraction grating, index of refraction, inherent phase difference, interference, light, path length difference, phase, phase difference, phase shift, reflection, thin-film interference, transmission, waves

What does this beetle and a soap bubble have in common?

This article explains how by having a thin-film the waves reflecting off of the boundaries between media can interfere and result in coloration.

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5 years 36 weeks ago
Interference and Colour, Part I - Diffraction Gratings Keywords: absorption, colour, diffraction grating, index of refraction, inherent phase difference, interference, light, path length difference, phase, phase difference, phase shift, reflection, thin-film interference, transmission, waves

What gives this beetle its rainbow colours?

This article describes how colouration of an object can arise due to interference of the light waves being reflected from the object.
Periodically arranged structures which act as point sources are one means of creating the condition that at certain angles only one specific wavelength will interfere constructively. The wavelengths that interfere constructively determine the colour of the object.
Examples of colouration in beetles by interference due to periodic structures is given.

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5 years 44 weeks ago
Interference and Colour Part III - Mathematics of Thin-Film Interference Keywords: absorption, colour, diffraction grating, index of refraction, inherent phase difference, interference, light, path length difference, phase, phase difference, phase shift, reflection, thin-film interference, transmission, waves

How can alternating layers in a beetle's shell give the beetle brilliant colour?

This article explains how to derive the conditions for constructive interference for thin-film interference and finds the thicknesses of alternating layers of melanin and protein to give constructive interference at 635 nm.

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5 years 34 weeks ago
Hydro-Electric Dams Keywords: dams, greenhouse gases, hydro-electricity, power

Why is this beautiful valley in north-eastern BC about to be flooded?

A look at the generation of power by a hydro-electric dam.

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7 years 19 weeks ago
Hydro-Electric Dam Demo Keywords: dams, hydro-electricity, power

Energy from Water?

An estimate of the power output from a model hydro-electric dam.

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7 years 15 weeks ago
How much do grade 10 students know about our energy consumption? Keywords:

Do students understand how similar we are to the machines we make?

The human body and the internal combustion engine are quite similar in that they are both heat engines requiring chemical energy to run.
By placing a question related to this notion on a national science contest, we attempted to discover what Grade 10 students think.

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5 years 24 weeks ago
How big was the aerodynamic force on Felix Baumgartner at 1342 km/h? (Or on Alan Eustace at 1321 km/h?) Keywords: aerodynamics, drag, felix baumgartner, free fall

Did you watch Felix Baumgartner jump out of a balloon gondola at an altitude of 39 km? Here's a question for your physics students, or even your physics teacher! How big was the drag force on Felix Baumgartner at his maximum speed of 1342 km/h? Pretty enormous, right? Wrong.

Knowing next to nothing about how aerodynamic drag varies as one hits the sound barrier, there is very simple way to assess the aerodynamic drag on a falling object at its maximum speed. Even at 1432 km/h. In fact the maximum aerodynamic drag occurs afterwards when the falling object is slowing down in the denser lower atmosphere. To asses how big the force was on Felix Baumgartner, we create a simple mathematical model of his fall.

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4 years 44 weeks ago
Home Heating Keywords: conduction, cooling, heat exchange, heat loss, heating

Where are these houses losing the most heat to the environment? The picture on the left is taken with visible light, that on the right is taken with infrared light with a wavelength of about 10 μm.

An example of how to model the heating and cooling of thermal systems, including a look at some of the issues surrounding the heating and cooling of buildings.

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7 years 18 weeks ago
Histograms, Measurement, and Uncertainty 4 years 2 weeks ago
Heating Efficiency Keywords: efficiency, electric, energy, gas, power

Which is better: gas or electric heat?

Calculating or measuring efficiency means tracking the power all the way from source to end-user.

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7 years 2 days ago
Heat Balance in the Human Body Keywords: calories, energy, energy use, evaporation, metabolic rate, power, sweat, thermal radiation, thinking

How much energy does our body use? How do we keep cool when it is really hot out? Can we justify eating more when studying?

Treating the human body as a thermodynamic system, with food energy going in and heat flow due to radiation, convection, evaporation and conduction, we can see how we can maintain a constant core temperature in a huge variety of environmental conditions.

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7 years 5 weeks ago
Generating Electricity: Wind and Water Keywords: electricity, electricity generation, hydro-electricity, Lend an Experiment (LEx), wind, wind energy, wind turbines

A match made in energy heaven, wind and water are wonderful sources of clean, renewable energy. Let us see what goes into this electricity generation by making some wind and water turbines ourselves!

This activity is part of the LEx (Lend an Experiment) Climate Kit. Students generate their own wind or hydro electric power by constructing wind/water blades, exploring how mechanical energy from external sources can be harnessed and turned into electrical energy. The effect of different gear ratios can also be explored.

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1 year 41 weeks ago
Generating Electricity Keywords: coils, electricity, electricity generation, magnetic field, magnets

Generating electricity using just a magnet and a wire?

A useful voltage can be obtained by moving a wire perpendicularly through a magnetic field; the electrons in the wire are pushed to one side creating a flow of electricity which is perpendicular to both the magnetic field and direction of wire motion.

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7 years 5 weeks ago
Food, Energy and the Environment Keywords: energy balance, Food, greenhouse gases

How do we feed nine billion people without destroying our environment?

The primary function of food is to provide our bodies with energy. Most of this energy comes ultimately from oil, with a little sunlight added, and its production is an energy-inefficient process.

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5 years 27 weeks ago
Flying Keywords: aircraft, birds, energy, flight, transport cost

It takes energy to fly. How much?

We examine how much energy it takes to fly from A to B, whether by bird, model glider, small plane or 747.

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7 years 10 weeks ago
Fan Efficiency Keywords: efficiency, electric fan, power

How can we measure the efficiency of an electric fan?

When you're out shopping for an electric fan, it might be a good idea to look for one that not only keeps you cool, but keeps your energy consumption low, too. Using an anemometer, Kill-A-Watt meter and a little bit of math, you can figure out how efficient your fan really is.

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4 years 49 weeks ago
Falling Cats Keywords: drag force, terminal velocity

Why does your cat have a better chance of surviving a fall from a large cliff than you do?

This example incorporates air resistance into free fall to derive the terminal velocity reached. The terminal velocities and physiology of cats and humans are compared.

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7 years 17 weeks ago
Energy Use in Cars 6: Gasoline Cars vs. Bicycles Keywords: air resistance, bicycle, energy use in cars, fuel economy, rolling resistance, vehicle transportation

When does a car have the same fuel efficiency as a bicycle?

A comparison of the energy cost of transportation between cars and bicycles.

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7 years 17 weeks ago
Energy Use in Cars 5: Gasoline Cars vs. Electric Cars Keywords: electric cars, energy use in cars, fuel economy, vehicle transportation

How do the greenhouse gas emissions of electric and gasoline cars compare?

A comparison of the energy cost and greenhouse gas emissions of gasoline and electric cars.

 

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7 years 17 weeks ago
Energy Use in Cars 4: Regenerative Braking Systems Keywords: energy use in cars, fuel economy, regenerative braking, vehicle transportation

What single system could be added to a gasoline car to improve its city driving fuel economy by 30-40%?

A calculation of the fuel consumption due to stop-and-go driving, for the purposes of estimating potential savings from a regenerative braking system.

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7 years 17 weeks ago
Energy Use in Cars 3: Rolling Resistance Keywords: energy use in cars, fuel economy, rolling resistance, vehicle transportation

Why does Natural Resources Canada recommend keeping your tires inflated to conserve gasoline?

A rough calculation of rolling resistance in cars explores the impact of having underinflated tires.

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7 years 17 weeks ago
Energy Use in Cars 2: Constant Speed Cruising Keywords: air resistance, drag, efficiency, energy use in cars, fuel economy, vehicle transportation

If a body in motion tends to stay in motion, why do we need to burn gas to travel at highway speeds?

Why do we need to burn gas to keep travelling at the same speed? The basic answer is "because if we didn't, eventually the car would stop." In everyday life, there is always friction and air resistance that opposes any motion, and if you leave a moving object alone, this friction and drag will eventually cause it to stop. This lecture looks at how this drag impacts a car.

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7 years 18 weeks ago
Energy Use in Cars 1: Stop-and-Go Driving Keywords: efficiency, energy use in cars, fuel economy, kinetic energy, vehicle transportation

When does cycling cost more in fuel than driving?

People recommend commuting by bicycle rather than by car to save energy. However sometimes when a cyclist pushes the button to make a traffic light change, it means that a bus full of people has to stop. When a cyclist makes the bus stop like this, is the extra fuel it has to burn to get back up to speed MORE than the fuel saved by choosing to commute by bicycle rather than car?

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7 years 18 weeks ago
Energy Efficiency and the Jevons Paradox Keywords: consumption, efficiency, energy, jevons, solid state lighting

Will increasing efficiency really reduce energy consumption?

Increases in energy efficiency have been shown to increase, rather than decrease, consumption.

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6 years 45 weeks ago
Energy Cost of Transport Keywords: energy, transport

How much energy does it take to move a person or a tonne of freight from A to B?

We compare how much energy it takes to move something from A to B using a variety of means: road, rail, water, air, and if that something is a human, walking and bicycling.

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7 years 10 weeks ago
Energy cost of flying Keywords: energy, energy loss, flight, potential energy

Gliders and planes glide similarly. How similar?

The power required to keep a toy plane flying can be inferred from the way it glides. This technique also works for full-sized aircraft.

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5 years 47 weeks ago
Energy and Power Keywords: definition, energy, types, useage

What is energy? Why is it such a useful concept? How does it relate to power?

Energy is the capacity to do work (both are measured in Joules). Power is the rate at which energy is transformed from one state to another, often from a stored state into work (a Joule of energy transformed per second is a Watt of power). Subsistence living requires about 200 W per person. Western living requires about 10 kW per person. Humankind currently uses about 12.5 TW of power, most from fossil fuels. Ten billion people living a western lifestyle (the not-impossible goal of many futurists) would require 100 TW of power.

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6 years 5 weeks ago
Energy and Greenhouse Gas (GHG) Calculations Keywords: carbohydrates, energy, GHG production

How much Chemistry and Biology do you need to understand to estimate energy and greenhouse gas production? Very little.

Gain a basic understanding of energy and GHG production calculations.

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7 years 19 weeks ago
Electric Shock Keywords: current, electric shock, electrical safety, electricity, electromagnetic induction, GFCI, ground fault circuit interrupter, induced emf, magnetic field, magnetic flux, protective devices, resistance, voltage

What effect does electricity have on the human body?

This article discusses the physiological effects of electric shock as well as a protective device installed in typically dangerous areas: ground fault circuit interrupters.

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7 years 6 weeks ago
Dimensional Analysis Keywords: checking answers, dimensional analysis, units

Unsure if your result makes sense?

Learn how to check if results make sense by analyzing the units involved in the calculations.

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7 years 18 weeks ago
Debating Tips Keywords: critical thinking, debate, denial, global warming

Having trouble recognizing and refuting bunk claims?

Some tips to help you in discussions where scientific data is being used to support or dispute a claim.

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7 years 18 weeks ago
Cycling and Showering Keywords: cycling, energy use, heat capacity, showering

Are cycle commuters, who take an extra shower, doing more damage to the environment than those who commute by car?

A recent letter to the Vancouver Sun claimed that commuting by bicycle was worse for the environment than commuting by car. The reason given was that if a cycle-commuter takes an extra shower at work (because cycling makes you sweaty), that burns the energy equivalent of a litre of gasoline, which is more than a car would burn on an average commute. Fact or rubbish?

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7 years 18 weeks ago
Cool Roofs Keywords: albedo, carbon dioxide, emission, energy, surface temperature

Can painting our roofs white offset tonnes of CO2 emissions??

In this article, we look at how we can save energy, reduce the Earth’s surface temperature and offset carbon dioxide emissions just by making our roofs and pavements a lighter colour!

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7 years 5 weeks ago
Comparing Energy and Heat Units Keywords: BTU, cost, energy, greenhouse gases, oil barrel, quad, R-value, thermal conductivity, thermal resistance, unit conversion, Watts

How do I compare heat and energy values given in different units?

A look at how to compare the costs of natural gas, gasoline and electricity and how to convert between various heat units including R-values, U-values, BTU/h, W and more.

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7 years 11 weeks ago
Commuting by car or cycle - which is better? Keywords: bicycle, Carbon footprint, consumption, cycling, energy, Food, spreadsheets

It's not actually that clear...

We set out to find how much of a change it would make environmentally if one cycled instead of drove to work and then further expanded our findings to include the variables of diet composition and material goods ownership.

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5 years 27 weeks ago
CO2e Keywords: carbon dioxide, CO2e, terminology

What does the "e" mean?

A brief primer on the meaning of "CO2e"

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5 years 26 weeks ago
Climate Models: Simulating the Earth Keywords: climate, climate change, simulating data

Climate models can give us a great deal of information about what sort of rules the climate follows and how the climate might look like in the future. A climate model is the result of a simulation run on a virtual Earth. This simulation mimics the real Earth and its climate as well as any influences the planet might have on the climate. They are used to predict the future of the climate using computers.

The prediction of future climate is done using climate models, virtual Earths with their climates simulated many years into the future. These virtual Earths live inside computers and evolve according to complex equations solved for points in time. The results that these climate models give provide us with important information to make decisions relating to climate change before we encounter the potentially catastrophic consequences.

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2 years 7 weeks ago
Clean Coal Keywords: energy, Fossil fuel, greenhouse gases, power

An oxymoron?

Calculating how much coal we have to burn in a typical large power station to produce 1 GWe for a year.

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7 years 15 weeks ago
Cheetah Chase Keywords: constant acceleration, displacement, kinematics, uniform motion, velocity

How far away can a cheetah be from a gazelle and still be guaranteed to catch it?

This example combines both constant acceleration and uniform motion to determine the maximum distance that a gazelle can be away from a cheetah for the cheetah to have a chance of catching the gazelle.

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7 years 17 weeks ago
Chaos, Frog Ponds, and Red Tide Keywords: Chaos, Complexity, Population Biology

Sometimes things are less complicated than they seem...

Under certain circumstances, simple equations can model complicated results. We can make a model of a frog pond that shows this type of behaviour. Sometimes this complex behaviour can lead us to identify incorrect, or not entirely correct, causes for the behaviour.

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5 years 33 weeks ago
Carbon Storage Keywords: carbon dioxide, carbon emissions

Are ways to perform human control of the carbon in the atmosphere? How do we do it? Is it safe?

Humanity is not without means to control the carbon dioxide in the atmosphere. There are ways it can be sucked out of the air and placed deep underground. However, this is by no means a permanent solution and is not without its risks.

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2 years 7 weeks ago
Capturing Solar Energy with Photovoltaic Cells Keywords: Lend an Experiment (LEx), photovoltaic cell, photovoltaics, resistance, solar, solar cells, solar energy

Did you know that the amount of power from a solar panel depends on what it's connected to? Explore how photovoltaic panels work, converting light into electrical energy, and learn how you can find the maximum power output from a solar panel.

This activity is part of the LEx (Lend an Experiment) Climate Kit. Students use solar panels to generate electrical power, exploring how light energy can be turned into electricity. Students connect the photovoltaic cells to different loads to find their peak power output.

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1 year 40 weeks ago
C21 Video Contest Top Videos 4 years 28 weeks ago
Bottle Rockets Keywords: air, bottle, force, fuel, pressure, rocket, thrust, water

Bottle Rockets - a future mode of transport?

This article explores the physics behind bottle rockets and how they work. It also discusses whether or not bottle rockets would be a viable means of transport.

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7 years 6 weeks ago
Blood Pressure Keywords: Bernoulli's equation, fluids

Why do you feel dizzy if you stand up too quickly?

This example investigates how the pressure in the major arteries will vary depending on the position of the body and some physiological consequences of such changes.

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7 years 17 weeks ago
Biofuel Keywords: biofuel, energy, solar radiation, transportation

Can plants be used to fuel my car?

A look at how much land is needed to plant corn so that the energy harvested is able to power a car for one year.

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7 years 17 weeks ago
Bicycling and Calories Keywords: air drag, conservation of energy, energy transfers, metabolic efficiency, rolling friction, work done

How long do you have to ride your bicycle to burn off a doughnut?

This example looks at the relationship between physical exercise and calorie consumption.

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7 years 17 weeks ago
Bicycle Power Keywords: bicycle, chi-squared, power, spreadsheets

How can you measure the mechanical power required to pedal a bicycle by observing how it slows down when you stop pedalling?

The forces acting on a bicycle can be estimated by observing the rate at which it slows down when you stop pedalling. This technique can, in principle, be used for any transportation vehicle.

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5 years 35 weeks ago
Bats and the Doppler Shift Keywords: bats, Doppler shift compensation, echolocation

What compensation for doppler shifts do bats perform to keep their echoes within their hearing range?

This example investigates the compensation for Doppler shifts bats perform to keep their echoes within their range of maximal hearing sensitivity.

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7 years 17 weeks ago
Balsa Gliders and 747s Keywords: air transport, balsa glider, Boeing 747, paper airplane, transport cost

Does throwing a balsa glider or paper airplane have anything to do with the fuel consumption of a Boeing 747?

Observing the flight of a model glider to infer some basic physics information that can be transferred to estimate the amount of energy necessary to run real full-sized aircraft.

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7 years 17 weeks ago
Balance of Rates: A Thought Experiment Keywords: carbon emissions, rates, unbalanced rates

We often look at the number of tonnes of carbon dioxide we emit into the atmosphere for a given activity. But what if it's not a question of how much- but rather, how fast?

We are pumping tens of billions of tonnes of carbon dioxide into the atmosphere each year. In contrast, the naturally occurring exchanges of carbon dioxide happen in the hundreds of billions of tonnes. Does this render our human activity insignificant? In this activity, we explore how even small differences in a balance can cause a large influence over time.

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1 year 40 weeks ago
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