It's the time we observe force
It sometimes needs a source
You might know a force that opposes motion
It's called friction
You surely know gravity
It's everywhere, even in an abandoned city
You might have a prior knowledge of objects that are magnetic
You see it isn't static
About forces, there's still a lot to learn
And it doesn't involve any fern
If you want to know who discovered gravity and how
Better not tell you now
You now know what sometimes needs a source
It's a force