1. The problem statement, all variables and given/known data An airbus A320 jetliner has a takeoff mass of 75,000 kg. It reaches its takeoff speed of 82 m/s in 35 s. What is the thrust of the engines? You can neglect air resistance but not rolling friction. (The force of rolling friction is given by Fr = [tex]\mu[/tex]r N 2. Relevant equations Fr = [tex]\mu[/tex]r N V = V0 + at [tex]\Sigma[/tex]F = ma T = thrust 3. The attempt at a solution The first thing i did was solve for the acceleration. I got 2.343 m/s2. From here I set [tex]\Sigma[/tex]F = T - [tex]\mu[/tex]r N = ma Thus: T = ma + [tex]\mu[/tex]r mg Then T = m (a + [tex]\mu[/tex]r g) So: T = 75,000kg (2.343 m/s2 + [tex]\mu[/tex]r9.8 m/s2) I don't know what the heck to do from here. There is no way I can calculate the coefficient of rolling friction, and it is not given. So I have 2 unknowns and 1 equation. Does this problem need more info?