I'm assuming that the force you posted is
(a) ...
(b) ...
once you find it, set and determine the x-value that minimizes W.
A 2.1 kg block is initially at rest on a horizontal frictionless surface when a horizontal force in the positive direction of an x axis is applied to the block. The force is given by (x) = (4.2 - x2) N, where x is in meters and the initial position of the block is x = 0. (a) What is the kinetic energy of the block as it passes through x = 3.3 m? (b) What is the maximum kinetic energy of the block between x = 0 and x = 3.3 m?
Thanks a ton.