From a displacement graph to a velocity graph

A particle moves along a straight line. Its displacement, \(s\) metres, from a fixed point is \(s=t^3-6t^2+9t\) for \(0\leq t\leq4\), where \(t\) is in seconds. Its displacement-time graph is shown.

1. State the times when the particle is at rest and explain how these are shown on the displacement-time graph.[2]
2. Find the velocity function. Sketch its graph for \(0\leq t\leq4\), labelling the intercepts, turning point and endpoints.[4]
3. Find the total distance travelled in the four seconds.[2]