A 5.0-m radius playground merry-go-round (a solid disk) with a mass of 160 kg is rotating freely with an angular speed of 1.0 rad/s. Two people, each of mass 60 kg, are standing right outside the edge of the merry-go-round and suddenly step onto the edge with negligible speed relative to the ground. Though numbers are given, calculations are welcomed but not required for this problem. (10 points)

(a) How does the total angular momentum of the system change from before the people step on to after? Increase, decrease, stay the same? Give you reasoning.
 

(b) How does the angular speed of the merry-go-round change after the two people have stepped on? Increase, decrease, or stay the same? Give you reasoning.