Half-Life 2 "Conservation of momentum" clipboard Thread

Hello everyone, I was able to identify the text written on the clipboard "Conservation of momentum", But i can't find out what the sixth word after the black line is. If you can see it what does it say?.

The text reads:

Conservation of momentum

Consider a rocket drifting in gravity free space. The rocket's engine is fired for time t and, during this period

For a multistage vehicle with (illegible) stages, the overall vehicle payload fraction depends on how the V

Here's a screenshot of the clipboard:

The (illegible) part reads "dissimilar" by the way

Good eye and thank you.