Question: can you tell me more about engey
James Marrow answered on 22 Jun 2011:
@drfc – great question
Energy is hugely important. It makes things move, it makes chemical reactions happen. Nothing changes without energy being involved. When something like a wheel moves, it has “kinetic energy”. If you slow it down by friction (sliding your hand over it), your hand will get warm (heat energy) as the wheel slows down and loses kinetic energy. We can store energy as kinetic energy (in a flywheel), or as chemical energy (in a battery or a fuel) for example, and then change it into electrical energy (to drive a motor) or heat energy (to warm ourselves up).
We get most of out energy from fossil fuels – these are a form of chemical energy. It’s been stored up over millions of years by plants that absorbed solar energy from the sunlight. We’re now using it very quickly, much more quickly than it was collected. If we want more energy, we will need to find other sources of energy, such as nuclear energy or solar energy (which we can capture from the light directly or from the wind and sea – these are driven by the sun)
William Eborall answered on 22 Jun 2011:
Energy is the ability to do work. It can exist in lots of forms. A battery stores energy in a chemical form which can be used to work electrical devices. A spring stores mechanical energy when you squash it which can be used to push against something. If you lift up a heavy object you are in a way storing gravity energy in your muscles – if you let go of the object the gravity energy will be used to pull the object back to the ground.
Energy can also be changed from one form to another. For example if you put your hands together and move them back and forwards against each other quickly your hands will heat up. This is your mechanical energy from the muscles in your arms changing into heat energy.
Is that the sort of thing you wanted to know about energy? Let us know and we can help more 🙂
Mike Dodd answered on 22 Jun 2011:
I always think the most important thing to know about energy is the three laws of thermodynamics:
1. Energy Can Be neither Created nor Destroyed.
This means that you can never create energy. The food you eat has energy stored in the fat and sugar. Plants convert energy from the sun into sugar, which is stored in the plant cells. When we eat the plants (say wheat), we break down the sugar and release the energy. This energy is used to run our cells and our body. When we move, we use the energy to contract our muscles to walk. The energy in your muscles is then converted to heat, which escapes your body. So at no point is energy created, it is just changed from sun light, to sugar, to ATP (for the muscles to work) and then heat.
2. The Entropy of an Isolated System always Increases.
This says that everything in the universe is getting more disordered. A good example of entropy is a students bedroom (like mine). When you clean it, you make it more ordered and entropy decreases. When you start to use your room, it becomes messy and more disordered and therefore the entropy increases. This happens with all molecules too. The more mixed up they are the more entropy they have.
3.The Entropy of a Perfect Crystal at Absolute Zero is Zero.
I can’t think of a good example of this one, sorry!
For more information visit this excellent BBC page of the 3 laws:
Suze Kundu answered on 22 Jun 2011:
The guys have covered a lot here, so I’ll leave you to read it, but if you have any more questions, I’ll try and answer, since they’ve done such a good job at giving you the facts!