Question about maximum Kinetic Energy?? KE & Work problem?? A 1.5 kg block is initially at rest on a horizontal frictionless surface when a horizontal force along an x-axis is applied to the block. The force is given by F(x) = (2.5 - x^(2))i 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 = 2.0 m ? b) What is the maximum kinetic energy of the block between x = 0 and x = 2.0 m ? I understand how to solve a but its part b that confuses me. Solution Guide states: "KE is maximized when F = 0. F = 0 when 2.5 - x^(2) = 0 x = √ 2.5 = 1.6 m Thus KE is maximized at x = 1.6 m " But why is KE maximized when F = 0?? Someone please explain to me. Thanks!