A drone of mass 1500 g flies horizontally north. The propellers produce a horizontal force of 4.2 N north. A constant air resistance acts south.
The speed of the drone increases from 2.0 m s−12.0\ \mathrm{m\,s^{-1}}2.0 ms−1 to 6.0 m s−16.0\ \mathrm{m\,s^{-1}}6.0 ms−1 in 2.0 s.
Calculate the air resistance acting on the drone.