A ram is the simplest hit in the arena and the most honest. There is no spin to bank, no gear trick. You bring your weight, you bring your speed, and the hit is the two multiplied together.
That is momentum (physics writes it p = mv). An 80 kg bot trundling at 5 carries the same punch as a 40 kg bot flying at 10. Double either one and the hit doubles. Note this is not the spinner's ω²: a ram is plain, linear momentum.
Momentum is a direction, not just a number. Catch your opponent dead center and all of it lands. Clip them at an angle and only the part pointed straight at them counts, the rest slides off:
A glancing hit throws your momentum away. This is why ram bots line up square before they commit.
Here is the part that makes weight so powerful: the same mass that powers your hit also keeps you from being thrown. How far a bot gets knocked back or flipped scales with one over its weight:
So a heavy bot is good twice over: it hits harder, and it is harder to move. A 30 kg bot taking a solid hit gets launched; a 120 kg bot eats the same hit and just shrugs.
If heavy is so good, why is anything light? Because weight is slow. A heavier bot accelerates sluggishly (it takes longer to reach the speed that makes a ram hurt), and it is less nimble. That is the whole trade: the heavyweight hits hard and stands its ground but lumbers; the lightweight darts and lands first but gets tossed. (The drivetrain side of this lives in Gear Ratios and Wheels vs. Tracks.)
| Real physics | In BotForge / RumbleBots |
|---|---|
| momentum = mass × speed | ram damage = mass × speed × aim × 1.2 × √(gear/5) × 0.45 |
| only the head-on component lands | aim is the alignment (dot) of your heading with the hit, 0 to 1 |
| lighter things get thrown further | knockback / flip magnitude ∝ damage × (50 / victim mass) |
| a sloped wedge deflects a blow | a front wedge cuts the damage it takes (×(1 - 0.6 × wedge)) and scoops the rammer up |
Six quick questions. Pick an answer to see why.