Two friends, al and jo, have a combined mass of 195 kg. at the ice skating rink, they stand close together on skates, at rest and facing each other. using their arms, they push on each other for 1 second and move off in opposite directions. al moves off with a speed of 10.2 m/sec in one direction and jo moves off with a speed of 11.4 m/sec in the other. assuming that friction is negligible, find al's mass.