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.
Corcord could go much faster, mach 2. Some military planes much faster still, mach 5. Mach is speed of sound but is not a fixed value. Speed of sound varies with air pressuure. At 35,000 feet (a typical cruising altitude for long haul), mach 1 is about 663mph. Faster planes have to fly higher for lower air resistance & better fuel economy.