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Asked by emmagrace to Dalya, Derek, Sarah, Tim, Tom on 19 Jun 2011.
Question: Whats energy?
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Sarah Thomas answered on 17 Jun 2011:
That is such a difficult thing to explain!
The word ‘energy’ comes from the greek language and means ‘activity’. I think of it as the ability of an enitity to make something happen, or in the case of stored energy, the potential to make something happen.
Without energy, nothing would ever change, nothing would ever happen. You might say energy is the ultimate agent of change.
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Tom Crick answered on 18 Jun 2011:
A great question: energy is an abstract concept, something that is only indirectly observed. Energy is measured in joules, which translate to “units of work”, which is always defined in terms of forces and the distances that the forces act through.
The total energy contained in an object is identified with its mass, and energy (like mass), cannot be created or destroyed — it is only converted into different forms.
Some examples that you may be familiar with are kinetic energy (when a mass is moving) or potential energy (e.g. a mass at the top of the building has “potential” energy due to gravity).
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Derek McKay-Bukowski answered on 19 Jun 2011:
What a fantastic question! So simple to ask, and yet so difficult to answer. As Tom says, it is an abstract concept. We use it as a way to measure action, activity of the potential for it to occur.
There are lots of forms of energy (electrical, mechanical, thermal, nuclear, and so on). Energy is conserved, which means that it never goes away. Sure, it might be turned into different forms, but it is always there somehow.
As Tom says, it is measured in units called “joules”. Don’t get this confused with “watts”, which is a measure of power. Power is energy per unit time (or joules per second). That leads into this little joke…
“Watt’s energy?”… “No, watts are power!”
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Tim Millar answered on 19 Jun 2011:
And to follow Derek “Who’s on first, Watts on second, I don’t knows on third…”
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