A particle whose mass is 3.0 kg is pushed along the x-axis with a time-varying force given by: F = 6.0 t2 − 2.0 t + 4.0. At t = 0, the particle is moving at a speed of 15 m/s. How fast (speed) is the particle moving at t = 3.0 s? ( F is in newton and t is in second)