A particle can only move along the x-axis. Forces act on it so that its potential energy function is: U(x) = 1 2 k1x 2 + 1 4 k2x 4 where k1 and k2 are positive. The particle is started at x = a with zero velocity. a. Where is the velocity a maximum? What is its magnitude? b. Where else will the velocity be zero? c. What is the force on the particle as a function of x?