Motion Lab.

Position is where the truck is right now, measured from the origin flag. Distance is how far it has actually traveled, which keeps adding up even if the truck reverses. Velocity is signed: positive means moving right, negative means moving left.

Newton's second law, F = m·a, links force, mass and acceleration. Add cargo and the same force produces less acceleration. Force and acceleration are two dials on the same physical state — set either one and the other follows.

Momentum is mass times velocity. At the same speed, a heavier loaded truck carries more momentum, so the same braking force takes longer and covers more distance to bring it to a stop.