So, to determine momentum, you need to know two things: mass and velocity. That's just a fancy way of saying "how heavy something is" and "how fast it's going". When you multiply these two things together, you get the momentum - and that's what tells you how hard it is to stop something.
Now, here's a fun fact: did you know that momentum is a vector? That means it's got both size and direction! It's like when you're playing a game of pool - the momentum of the cue ball isn't just about how fast it's going, but also where it's going.
