Every bot has a center of mass: the single point where all its weight balances, like the spot you could hold it up from with one finger. Heavy parts pull it toward them. A battery low in the floor pulls it down; a spinner on a tall mast pulls it up.
That balance point decides two different things.
A bot stays upright as long as its center of mass sits between the wheels. Tilt it far enough that the balance point passes outside the wheels, and gravity takes over: it falls. A wide wheelbase and a low center of mass mean you can lean a long way before that happens.
Wider wheels or a lower center of mass both make that angle bigger, so a harder shove is needed to tip you. A heavier bot also resists a shove: the same hit tilts a heavy bot less than a light one. In BotForge this shows up as the Footprint stat, which warns TIP RISK if your center of mass is already outside the wheels.
A dedicated flipper scoops underneath you and launches you straight up. Your wheelbase barely matters here: a wide stance stops you being shoved over, but a flipper does not push sideways, it lifts. So the lab above (a shove test) is only half the story.
What actually resists a flipper is a low center of mass (a top-heavy bot is up to 2 times as likely to flip; a low one only half as likely) and plenty of mass (heavy bots are harder to launch). If you cannot stay low, build an invertible bot that fights upside-down and ignores flips entirely.
A flipped bot is nearly helpless: wheels off the ground means no driving, and most weapons cannot reach. You wait out a referee count (about 12 seconds) or self-right with an arm (a "srimech", which works about half the time and costs power). Some invertible bots are built to work upside-down and ignore flips entirely.
In the Stability Lab, set a shove force, read the prediction, then press SHOVE IT to test it. Try to build a bot that survives a full-strength slam.
For teachers Physics, science and engineering, middle school through high school
Find a bot's balance point, then shove it. Discover why heavy parts mounted low and a wide wheelbase make a bot nearly impossible to flip, while a tall top-heavy bot tips on the first hit. The same rule drives the Flip Resistance stat in BotForge.
In class: Move a heavy part up and down, widen the wheelbase, and shove the bot. Students predict which build tips before pressing the button.
Students need no account and nothing to install, so it works on Chromebooks and as a sub plan.
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