I'm trying to solve a problem which involves the following scenario. Any help would be great! A landing aircraft (mass 14 tonnes) is to be slowed from 300km/hr to 180km/hr in 3 seconds, by the deployment of two identical parachutes at its rear. Determine the diameter of each parachute. The landing is done at sea level in standard conditions. So far: - Drag coefficient of the parachute is 1.2 - Density of air is 1.23kg/m^3 - 300km/hr = 83.3 m/s - 180km/hr = 50 m/s F = M.A F = 14000 * (83.3-50)/3 F = 15400 N What I'm unsure of is what to use as V in the drag coefficient equation. I assume this requires me to integrate, but I'm not exactly sure what to integrate. I'd really appreciate any help offered!