Question

An airplane has mass of 5,320 kg. At takeoff, how much lift force is necessary to accelerate the plane upward at a rate of 1.40 m/s2?

Answer 1

Use the formula of Newton 2nd law: F-R=ma, where F is driving force, R is the Resistive force, m is mass and a acceleration. Hence R is force due to weight or mg or 5320*9.81=52189.2N
So F=R+ma or 52189.2+5320*1.4=3.89*10^8Newtons.

Answer 2

My mistake. All my steps are correct. Somehow I or the calculator missed the calculation. Doing R+ma=F = (1.4*5320)+(9.81*5320)= 59637.2N or your third alternative.