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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 4 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 4 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 4 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 4 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 4 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 4 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 5 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 5 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 5 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 5 weeks ago
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