A particle moving in the x direction is being acted upon by a net force F(x)=Cx^2, for some constant C. The particle moves from x initial =L to x final=3L. What is Delta K, the change in kinetic energy of the particle during that time? I tried thih by doing the integral of F(x), replacing x with 2L (because final-initial, 3L-L). I got the answer 2/3 CL^3, and its telling me I am off by a multiplicative factor. Is this becuase I did the integral wrong, or am I missing something? Thanks!