1. The problem statement, all variables and given/known data A helicopter with a mass of 2090 kilograms accelerates up at 3.13 meters per second per second. What lift force is exerted by the air on the propellers? m = 2090 kg a = 3.13 m/s/s 2. Relevant equations F = ma ? 3. The attempt at a solution Force = 2090 kg * 3.13 m/s/s = 6541.7 N Which is apparently incorrect, then I thought I might have read it wrong and I tried -6541.7, which is also wrong. Can anyone tell me what I am doing wrong? Did I forget to factor something in?