Emily is pushing a box weighing 10 kg on a surface. The box and surface have a static friction coefficient of 0.5 and a kinetic friction coefficient of 0.4. If Emily pushes the box with a force of 50 N, what is the box's acceleration??

For this problem, I first calculated the Normal force so I could use the equation μ(s)*N = f(s). I did this and found out that f(s) is 49, so the static friction is 49 N. I subtracted 50 N- 49 N and got 1 N. Therefore, there is 1 N of energy left over. Since 1 N is 1 m/s^2 acceleration for 1 kg, I figured that 1 N is 0.1 m/s^2 acceleration for 10 kg. However, the correct answer is 1.1 m/s^2. Can someone explain this to me??