A point starting with velocity 21 cm/s has time at time seconds an acceleration cm/s/s. Show that it stops and reverses its direction of motion at the end of 3 seconds, and find how far it is then from the starting point.
Source: Rosenberg, R.L. (1984). Elementary Calculus: Course Notes. Ottawa, Canada: Holt, Rinehart and Winston. (Exercise 6: Question 3(i), p. 21)