Energy rate density

Energy rate density is like how much power you can get from something per unit of space. Think of it like how much candy you can fit into a tiny bag.

Imagine you have two boxes: one big box and one small box. And let's say you have candy that you want to put in these boxes. If you put the same amount of candy in each box, the big box will have a lower candy rate density because the candy is spread out over a larger space. But, the small box will have a higher candy rate density because there is less space for the same amount of candy.

Similarly, energy rate density is the amount of energy you can get from a certain amount of space. For example, if you have a small battery and a big battery and they both have the same amount of energy, the small battery will have a higher energy rate density because it has less space for the same amount of energy.

So, when we talk about energy rate density, we're basically talking about how much energy you can get from a certain amount of space, just like how many candies you can fit in a certain amount of space.