Final answer:
The Mach number, which represents the ratio of an object's speed to the speed of sound, is 0.8 when the object's velocity is 800 ft/s and the local speed of sound is 1000 ft/s.
Step-by-step explanation:
The Mach number is a dimensionless quantity in physics used in aeronautics to represent the ratio of the speed of an object to the speed of sound in the surrounding medium. In the given scenario, where a velocity of 800 ft/s is compared to the local speed of sound at 1000 ft/s, the Mach number would be calculated as the ratio of these two values.
To find the Mach number, you divide the object's velocity by the speed of sound:
Mach number = Velocity / Speed of sound
In this example, the calculation would be:
Mach number = 800 ft/s / 1000 ft/s = 0.8
So, the Mach number in this case is 0.8.