How fast to bullet trains travel?
Beijing–Shanghai high-speed railway
The railway was completely electrified in 2006. On April 18, 2007, the new CRH bullet train was introduced on the upgraded railway as part of the Sixth Railway Speed-Up Campaign. A day-time train D31 served the route, departing from Beijing at 10:50 every morning, and arriving at Shanghai at 20:49 in the evening, travelling mostly at 160–200 km/h (up to 250 km/h in a very short section between Anting and Shanghai West). In 2008 overnight sleeper CRH trains were introduced, replacing the locomotive-hauled Z sleeper trains. With a new high-speed intercity line opening between Nanjing and Shanghai in the summer of 2010, the sleeper trains made use of the high-speed line in the Shanghai–Nanjing section, travelling at 250 km/h for a longer distance. The fastest sleeper trains took 9 hours, 49 minutes, with four intermediate stops, at an average speed of 149 km/h.
Rifle
Bullets leaving a rifled barrel can spin at a rotational speed of over 100,000 revolutions per minute (rpm, or 1.67 kilohertz) depending on the muzzle velocity of the bullet and the pitch of the rifling. The rotational speed of the bullet can be calculated by using the formula below. The formula divides the number of inches in a foot (12) by the rate of twist that the barrel has. This number is multiplied by the muzzle velocity (MV) and the number of seconds in a minute (60). For example, a bullet with a muzzle velocity of leaving a barrel that twists once per foot (1/12") would rotate at 180,000rpm.