meter per second squared

An acceleration of one metre per second squared adds one metre per second of speed with every second that passes, so a car reaching 100 km/h (27.8 m/s) in ten seconds averaged 2.8 m/s². Free fall is 9.81 m/s², lifts are held to roughly 1 to 1.5 m/s² for comfort, and metro trains pull away at about 1 m/s². The ceiling for braking a road car is set by tyre grip rather than brake power: with a friction coefficient near 1 on dry asphalt, no ordinary car can decelerate much beyond 9 or 10 m/s², which is why every emergency stop tops out near 1 g regardless of what the brochure says about the brakes.

This is the unit the kinematics solvers on this site expect, because with metres and seconds throughout, $v = u + at$ and $s = ut + \tfrac{1}{2}at^2$ run without conversion factors and $F = ma$ delivers newtons directly. Gravity science keeps a named CGS relative alive: the gal, 1 cm/s² with symbol Gal, honours Galileo, and gravity surveys map anomalies in milligals, each 10⁻⁵ m/s², fine enough to reveal the buried density contrasts that mineral and groundwater exploration look for.