

:: Section 3Newton's Resistance Law and Stokes's Law
I. Newton's LawIf you drop a ball, it falls due to the gravitational force. Meanwhile, the resistance of gas molecules (drag) tend to slow down the movement. To describe the drag force resulting from gas resistance, F_{D}, the following equation can be used: where C_{D } is the drag coefficient. This is the general form of Newton's resistance equation. This Newton's resistance equation is valid in the turbulent flow regime (i.e. Re_{p }> 1000), where inertial forces are much larger than viscous forces. The drag coefficient C_{D} has a nearly constant value of 0.44.
To calculate the Re_{p} values, you can use the webcalculator below:
