A particle moves along the -axis, its position at time given by x(t) =t/(1 + t2), t > 0, where is measured in seconds and in meters.
(a) Find the acceleration at time t. When is it 0?
(b) Graph the position, velocity, and acceleration functions for 0 < t < 4.
(c) When is the particle speeding up? When is it slowing down?