A particle of mass 3.25 kg has a net force applied to it, The Force (Fx) vs. time graph shown below. Both portions of the graph are linear. The particle's initial velocity is vx (0) = 27.0 m/s. The force at x = 0 is 35.0 N E. (N) 25 30 35 SI OI S0 0 1 2 3 5 6 7 7.5 s 8 t(sec) a. What is the particle's acceleration and velocity at t = 3.0 s? b. What is the particle's acceleration and velocity at t = 7.5 s?