Hello! First time poster, please treat me well! I've already solved the problem below on my second attempt with the help of kinetic energy but I want to know why my first attempt gives a wrong answer. 1. The problem statement, all variables and given/known data A force in the +x-direction with magnitude F(x) = 18.0 N - (0.530 N/m)x is applied to a 6.00-kg box that is sitting on the horizontal, frictionless surface of a frozen lake. F(x) is the only horizontal force on the box. If the box is initially at rest at x = 0, what is its speed after it has traveled 14.0 m? 2. Relevant equations a = F/m 3. The attempt at a solution F(x) = 18.0 - 0.530x => a(x) = 18.0/m - 0.530x/m => Integrate => v(x) = 18.0x/m - 0.530x2/2m = 3x - 0.530/12 x2 v(14) = 33.3 Why is this incorrect? I'm guessing that the integral of a(t) is velocity but the integral of a(x) is something else.