Weight loss. If your cat is overweight, you will want to feed for 2 pounds less, or 40 fewer calories a day, and readjust every time your cat loses a pound, until you hit a healthy weight, and then maintain.  Differences in metabolism.
Since the speed of sound through the standard atmosphere is 761 mph (1,223 km/h) at sea level, Mach 2 then follows as 1,522 mph (2,447 km/h). If you were to ask how fast is Mach 2 at an altitude of 30,000 ft (9,150 m), we would use the same methodology to find out that it is only 1,356 mph (2,180 km/h) because the speed of sound generally decreases as altitude increases.
Mach 1.0 is the speed of sound. Most airliners travel at mach .7 The Concorde travelled at 1350 mph, but as we all know it is long gone. Since I bring a portable GPS with me, and some enlightened airlines allow it above 10,000 feet, I can see where I can, and how fast we are going.