It's about as fast as a Peregrine Falcon.
(a.k.a. Peregrine, a.k.a. Duck Hawk, Falco peregrinus)
The Peregrine Falcon can reach speeds of up to 210 knots when diving. Falcons are sometimes sent to scare smaller birds away from airports to improve air traffic safety and were used in World War II to intercept carrier pigeons used by enemy forces.
It's about one-and-one-tenth times as fast as The CRH (train).
In other words, the speed of The CRH (train) is 0.910 times 210 knots.(a.k.a. Hexie Hao, 和谐号, a.k.a. 和諧號, a.k.a. Héxié Hào, a.k.a. "Harmony")
The CRH-3 train which runs on China's Beijing-Tianjin Intercity Railway are capable of speeds up to 190 knots. Theses train can make the 120 km (74 mi) journey from Beijing to Tianjin in about 30 minutes.
It's about one-and-one-fifth times as fast as a Porsche 911.
It's about one-and-one-fifth times as fast as a Lamborghini Gallardo.
It's about one-and-one-fifth times as fast as The TGV (train).
In other words, the speed of The TGV (train) is 0.830 times 210 knots.(Train à Grande Vitesse) (for SNCF TGV Réseau, a.k.a. "Network" model, a.k.a. TGV-R) (maximum speed)
The TGV Réseau sets have a top speed of 170 knots. The train is capable of travelling the 425 km (264 mi) distance from Paris to Lyon in East-Central France in about two hours.
It's about one-and-one-fifth times as fast as an Arrow (archery).
In other words, 210 knots is 1.2050 times the speed of an Arrow (archery), and the speed of an Arrow (archery) is 0.82990 times that amount.(250 g arrow fired from 60#/28" bow)
A 250 gram arrow will reach speeds of approximately 174.30 knots when fired from a 60-lb, 28-inch draw bow . Archeological evidence from the Ahrensburg valley near Hamburg, Germany indicates that arrows have been used since at least 11 to 12,000 years ago.
It's about one-and-two-fifths times as fast as a Helicopter.
In other words, 210 knots is 1.370 times the speed of a Helicopter, and the speed of a Helicopter is 0.730 times that amount.(for AH-64A Apache, a.k.a. Hughes Model 77) (maximum cruise speed)
The AH-64 helicopter, one of the primary helicopters used by the United States Army, flies at a top cruise speed of 153 knots. The AH-64 is the primary military helicopter of several nations including the United States, the United Kingdom, Israel, Japan, and the Netherlands.