3.1 What is Energy?
| Site: | Cowichan Valley School District - Moodle |
| Course: | Science 10 with CSS teacher |
| Book: | 3.1 What is Energy? |
| Printed by: | Guest user |
| Date: | Wednesday, 2 July 2025, 12:41 AM |
Bill Nye - Energy
What is Energy?
Energy is often defined as:
Energy is a property of objects which can be transferred to other objects or converted into different forms
or
Energy is the ability to do work.
| Energy in Food |
| One of the mose powerful things about working with energy is that it can be represented in SO many forms. We can even measure the energy within our food. Energy from food is usually measured in joules or calories. |
Gameshow Examples
Potential & Kinetic
Facts about energy:
- Energy is most typically measured in Joules.
- Food energy can be measured in Joules or Calories.
- Energy can be converted from one form to another.
- Unlike Force or Velocity, energy is a scalar quantity (no direction).
| Units for Energy |
|
Quote from famous physicist (Richard Feynman, 1964 For those who want some proof that physicists are human, the proof is is the idiocy of all the different units which they use for measuring energy. Energy (in all its various forms), has been measured in calories, btu's, foot-pounds, kilowatt-hours, eV, tons of TNT, tons of oil, tons of coal....etc. Any of these can be converted to Joules. In this course, we'll pretty-much stick to Joules when we measure or calculate energy. |
Gameshow Examples
Friction
You've learned a bit about friction before.
Let's review a few things:
- friction always opposes motion
- any two surfaces rubbing will cause friction
- the rougher the surface, the greater the friction
- friction creates heat
- kinetic friction means friction while moving (hint: "kinetic" means moving)
- static friction means friction while not moving (hint: "static" means stationary)
So, let's relate this to energy:
- friction causes energy conversion
- the energy created by friction is heat (thermal) energy
Most often, friction get's a "bad rap."
- it would be so much easier to swim fast without all the friction of water
- I wish my shoes wouldn't give me blisters
- cycling could be so much faster without the air resistance
- it would be so nice to have more efficient cars
- NASA has spent billions trying to figure out how to handle the heat of friction upon reentry into the atmosphere by the space shuttle
- playing soccer in long grass is painful as the passes never get far enough
- I need to wax my skis because they're getting too slow (snow friction)
Sometimes, though, we realize that life without friction would not be good.
- I'd like more friction so my brakes worked better
- the lack of friction on icy days makes driving unsafe
- I wish I had more friction when trying to open a jar
- when I crash when biking, the road sure makes nasty scars
- running on ice certainly makes you appreciate friction
- good tires sure make your car or bike handle nicer
- when I'm cold, it helps to rub my hands together
| Energy Lost due to Wind Resistance |
| Wind resistance is another form of friction. The faster you go, the greater the wind resistance and the more energy you need to overcome. When traveling at 80 kilometres per hour, the average car uses around half of their fuel energy just to overcome the wind resistance. |
Examples
Practice Quiz:
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1. Energy loss due to friction is: |
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2. Devices used to convert kinetic energy to heat is: |
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3. Friction can: |
| Holes in Disc Brakes |
| There are three main reason that manufacturers add holes to disc brakes 1) reduce weight of the disc 2) allow the disc to cool more during long descents and 3) to allow another place for water to move off the disc. |
Simulation
Consider this situation in terms of energy conversions.
Sourcing from bbc.co.uk
Interview
What do physicists, technologists, and engineers do? Here's an example.