1. The problem statement, all variables and given/known data Mass of the bus is 20 tons. It accelerates to 10 m/s (from initial speed of 0) in 50 meters. Find the coefficient of friction (u) if the force, that pushes the bus = 14*10^3 N m=20t=20000kg S=50m v=10m/s F=14kN=14000N 3. The attempt at a solution So we can find out what the acceleration is using a=2S/v^2 And it will be equal to 1 m/s^2 But, the total force F(total)=F-F(friction)=m*a=14000-F(friction)=20000 So it turns out Force of friction = -4kN. How can this be, what did I do wrong?