Momentum

🧠 Memory Aid

p = mv — "Pretend Mass is Velocity's bodyguard": Momentum (p) is calculated when mass (m) and velocity (v) work together. The unit kg m/s reminds you it includes both kg (mass) and m/s (velocity).

Conservation — "The Ledger Rule": Think of momentum like money in a ledger. It can be transferred between objects (like transferring money between accounts) but the TOTAL amount never changes — it's always balanced.

Direction tip: Pick one direction as positive (e.g., right = positive, left = negative). An object moving left has negative momentum. Stick to your chosen convention throughout the whole problem!