I’ve been behind on posting these, but here’s four on the theme of energy to bring me up to date.

04 – Conservation of energy

Here’s a fact that may make you annoyed,
But the truth of it’s hard to avoid.
All around we can see,
We can move energy,
But it just can’t be made or destroyed.

A relatively simple restatement of the Principle of Conservation of Energy

05 –Kinetic Energy

It is time for me to wax poetic,
About energy that is kinetic.
If an object does slow,
It’ll have less you know,
Yet more if it gets more frenetic.

Kinetic Energy is probably the easiest to describe – it’s associated with movement. An object with higher mass or speed will have a higher kinetic energy – in classical mechanics it is given by $E = \frac{1}{2}mv^2$, but like most things gets more complicated as the speed increases to an appreciable fraction of the speed of light.

06 – Gravitational Potential

When climbing a hill you just might,
Be gaining a bit more than height.
At the peak it is found,
That compared to the ground,
Your potential is higher – that’s right!

This is a simplification given it doesn’t take into account the mass of the mountain etc, but generally speaking by moving two masses further away from each other you’ll increase the gravitational potential energy of the system made up of those two masses.

07 –Electrical Potential Energy (EPE)

For EPE there is an art,
Taking opposite charges to start.
EPE will depend,
On their start and their end.
It increases as they move apart.

And an analogous limerick for the energy associated with electric rather than gravitational fields – electric potential energy. Again I’ve gone for a simple situation, ignoring the possibility of a collection of more than two charges, and what happens when you have similar charges (both positive or both negative), rather than the one positive and one negative I’ve talked about here. What do you expect in such a limited number of syllables?

Thanks to for suggesting the topic of energy via Twitter. Got something related to physics you’d like me to explain through the medium of limericks? Let me know in the comments!