The Velocity of a Particle Moving Along the X Axis

Multiple Choice

The velocity of a particle moving along the x axis is given for t > 0 by vx = (32.0t − 2.00t3) m/s, where t is in s. What is the acceleration of the particle when (after t = 0) it achieves its maximum displacement in the positive x direction?

A) −64.0 m/s²
B) zero
C) 128 m/s²
D) 32.0 m/s²
E) −32.0 m/s²