How is the efficiency of a rocket launch calculated when the weight keeps changing with fuel being spent + stages detaching?

Question

I assume it has to be a really complex calculation, how is the weight accounted for when the target number keeps changing constantly so dramatically?

In: 5

Answer 1

The most basic form of the rocket is basically a tube that farts out burned fuel. As you have said the weight of the rocket is not constant, which might make the problem sound complicated, but dealing with changing quantities is the essence of CALCULUS.

with a bit of calculus tinkering, you can derive the “rocket equation”(google keyword), which basically allows you to calculate the change in speed with the fully fueled mass, empty mass and exhaust velocity

Not exactly 5 yo, but [here’s](https://www.youtube.com/watch?v=bPXjkFAnQio) how you can derive the “rocket equation”,