4. A motorcycle and rider have a combined mass of 275-kg. (a) What is required impulse needed to bring the motorcycle and rider to rest if they have an initial

velocity of 20.0 m/s [W]? [2 marks] (b) If the wheels exert an average force of 710 N [E] to the road, what is the time needed for the rider and cycle to come to rest? [2 marks]