Consider an artificial satellite orbiting the Earth and suppose that the atmosphere co-rotates with the Earth. I need to calculate x, y and z components of the atmospheric drag. I know how to calculate the drag in a non-spinning atmosphere and I have all the data to do that, but the Earth’s rotation confuses me. I know the x, y and z components of the satellite state (position and velocity). The z-axis is the Earth’s rotation axis and the x-axis and y-axis lie on the equatorial plane. The exes do not rotate (it’s an inertial reference frame). Please, could somebody help me?