1. The problem statement, all variables and given/known data A 2000 kg plane is landing at an airfield with an initial speed of 50 m/s. The force of friction is 1/4 the weight of the plane. What is the acceleration of the plane? 2. Relevant equations Fnet = ma Fnet = something - ff 3. The attempt at a solution 2000a = thing I don't know - ff, which is 500 n So 2000a = ? - 500N What force am I missing?