A rock is being pulled down by a net force of 10N. The rock falls at an acceleration of 2m/s/s. What is the rock's mass?

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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?

Why do different substances have diffrent properties