A mother and son are roller-skating together. The mother is standing still in the middle of the rink and the son runs into her from behind, skating as fast as he can. When he runs into his mother, he grabs onto her legs and they roll forward together at 2.21 m/s. The mother's mass is 54.7 kg, and the son has a mass of 33.1 kg. What is the son's velocity just prior to the collision?

I) a gas contained within a piston-cylinder assembly undergoes two processes, a and b, between the same end states, 1 and 2, where p1 = 10 bar, v1 = 0.1 m3 , u1 = 400 kj and p2 = 1 bar, v2 = 1.0 m3 , u2 = 200 kj: ' process a: process from 1 to 2 during which the pressure-volume relation is pv = constant. ' process b: constant-volume process from state 1 to a pressure of 2 bar, followed by a linear pressure-volume process to state 2. kinetic and potential energy effects can be ignored. for each of the processes a and b, a) sketch the process on a p-v diagram. b) evaluate the work, in kj. c) evaluate the heat transfer, in kj.(ans : qb,12 = -65.0 kj)