IoP Energy
https://spark.iop.org/collections/energy-new-curriculum#gref
https://spark.iop.org/energy-cpd-videos
What is energy?
“The property of matter and radiation which is manifest as a capacity to perform work (such as causing motion or the interaction of molecules).”
‘It is not a description of a mechanism, or anything concrete; it is just a strange fact that we can calculate some number and when we finish watching nature go through her tricks and calculate the number again, it is the same.’ Richard Feynman
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It’s easy to go wrong
‘The moving pencil uses kinetic energy.’ (QCA)
‘The steam [from a volcano vent] is converted into energy and transported to Europe via a 1,200-mile sea-floor cable.’ (a London newspaper)
‘Carbonaceous matter is converted to heat or other forms of energy.’ (Physics World)
‘Energy makes things happen.’ (ASE Big Ideas)
‘The bulb lights because energy flows from the battery to the bulb.’ (Sophie, Year 9)
Common Misconceptions about Energy
Energy is truly lost in many energy transformations.
There is no relationship between matter and energy.
If energy is conserved, why are we running out of it?
Energy can be changed completely from one form to another (no energy losses).
Things “use up” energy.
Energy is confined to some particular origin, such as what we get from food or what the electric company sells.
An object at rest has no energy.
The only type of potential energy is gravitational.
Gravitational potential energy depends only on the height of an object.
Doubling the speed of a moving object doubles the kinetic energy.
Energy is a “thing.”
The terms “energy” and “force” are interchangeable.
From the non-scientific point of view, “work” is synonymous with “labor.” It is hard to convince someone that more “work” is probably being done playing football for one hour than studying an hour for a quiz.
Why these are wrong:
treat energy as a substance (when it is a calculation tool)
are ambiguous and inconsistent
Use energy like phlogiston
give causal powers to energy
Vis Viva becomes “energy” in 1802
Thomas young.
Though it is often reported that Joule took a thermometer with him on his honeymoon, and made measurements of the temperature of a waterfall, Joule’s biographer reports that the story only appeared 35 years after the alleged event and is likely a fable.
Aside: https://spark.iop.org/stories-physics
What do we teach about energy…
In physics, energy is a property of objects which can be transferred to other objects or converted into different forms, but cannot be created or destroyed.
The purpose of teaching energy is to do calculations — it is about amounts
Energy is just a number.
So:
•Forces tell you WHY things happen
•Energy tells you IF they can happen
How much energy:
1 tonne of water flowing down a 100 metre hill
1kg of boiling water cooling down
A 2 tonne truck at 70 mph coming to rest
Burning 20g of nightlight candle
Lying in bed for 4 hours.
1,000,000J or 1MJ
A 2 tonne truck at 70 mph coming to rest
How much energy will be gained by the brakes, air etc when the lorry has come to a stop?
Things we know:
1.The purpose of teaching energy is to do calculations — it is about amounts
2.Energy is always conserved.
3.Energy is just a number.
4.The numbers always add up.
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https://www.dropbox.com/sh/ruffc3qpi95by7x/AABzd5AH1Ei-cT_0VJs3-K9Da?dl=0?dl=0
https://www.dropbox.com/sh/ruffc3qpi95by7x/AABzd5AH1Ei-cT_0VJs3-K9Da?dl=0
Sankey Diagram
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Lets play!
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If students have access to a few of these toys and the time to play, a lot of questions arise:
Which toy will achieve the greatest height?
Which toy will jump first? Why?
What height will the toy achieve jumping upside down?
You can lead them further with a few well placed questions:
How much force do you need to compress the rubber?
The toy will undergo an acceleration: When will this acceleration be at its maximum? What would increase it or decrease it?
How could I make it jump higher?
What happens if you stack two of them?
https://www.dropbox.com/s/moj2qqa4l8za5wp/RMfI2jL6lTZjoeoH.mp4?dl=0
More power than Yoda?
Following from:
First we need to know how heavy the ship was. The X-Wing’s mass has never been canonically established, but its length has—12.5 meters. An F-22 is 19 meters long and weighs 19,700 kg, so scaling down from this gives an estimate for the X-Wing of about 12,000 lbs (5 metric tons).
$$m_{x} = m_{f22} \times \left(\frac{12.5}{19}\right)^{3} \approx 5,600\mathrm{kg}$$
The front landing strut rises out of the water in about three and a half seconds, and I estimated the strut to be 1.4 meters long (based on a scene in A New Hope where a crew member squeezes past it), which tells us the X-Wing was rising at 0.39 m/s.
Lastly, we need to know the strength of gravity on Dagobah. Here, I figure I’m stuck, because while sci-fi fans are obsessive, it’s not like there’s gonna be a catalog of minor geophysical characteristics for every planet visited in Star Wars. Right?
Nope. I’ve underestimated the fandom. Wookieepeedia has just such a catalog, and informs us that the surface gravity on Dagobah is 0.9g. Combining this with the X-Wing mass and lift rate gives us our peak power output:
$$\frac{5,600 \mathrm{kg} \times 0.9\mathrm{g} \times 1.4 \text{ meters}}{3.6 \text{ seconds}} = 19.2\mathrm{kW}$$
Viral Story:
(Energy) Resources:
https://www.smbc-comics.com/index.php?db=comics&id=2305
https://www.gridwatch.templar.co.uk/
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Resources (teaching)
https://www.dropbox.com/sh/1j8xvbgtdsmv0sf/AADcAVs3whptFUz1k21SWEwka?dl=0?dl=0
https://www.dropbox.com/sh/1j8xvbgtdsmv0sf/AADcAVs3whptFUz1k21SWEwka?dl=0
https://www.dropbox.com/sh/e34iju1d8dahgxv/AACesqKdMaMzn06e1vmnnaXOa?dl=0?dl=0
https://www.dropbox.com/sh/e34iju1d8dahgxv/AACesqKdMaMzn06e1vmnnaXOa?dl=0