Convert mile per square hour to gravitation (earth)

The unit g is the standard acceleration of free fall at the Earth's surface, about 9.81 m/s²; a car braking hard reaches about 1 g, a roller coaster 3–4 g and a fighter pilot 9 g, and the value on the Moon is only a sixth of Earth's. The gal, named after Galileo, is 1 cm/s² and is used in geodesy and gravimetry, where variations in gravity of a few milligals reveal ore bodies, oil fields and the movement of magma.

Acceleration is the rate at which speed changes, and 1 m/s² means gaining 3.6 km/h every second. A family car that reaches 100 km/h in 10 s averages 2.8 m/s²; a sports car doing it in 3 s averages 9.3 m/s², roughly 1 g, which is also what an emergency stop on dry tarmac achieves. Trains pull away at about 1 m/s², and lifts keep below 1.5 m/s² for comfort. The kilometre per hour squared is mostly a curiosity: 1 m/s² is 12,960 km/h².