What is the most important source of energy that our body craves more than any other?

Asimply means that over time there was some sort of change.

If an athlete runs once around a track, back to the starting line, her average velocity is zero. true or false?

An important dimensionless parameter concerned with very high-speed flow is the mach number, defined as v/c, where v is the speed of the object such as an airplane or projectile, and c is the speed of sound in the fluid surrounding the object. for a projectile traveling at 1170 mph through air at 50 ˚f and standard atmospheric pressure, what is the value of the mach number?