Two ice skaters, with masses of 40 kg and 85 kg , are at the center of a 50 m -diameter circular rink. The skaters push off against each other and glide to opposite edges of the rink. If the heavier skater reaches the edge in 30 s , how long does the lighter skater take to reach the edge?

Answer 1

momentum is conserved
... the two skaters have equal but opposite momenta
... M1 * V1 = M2 * V2

85 * (25 m / 30 s) = 40 * v
... solve for the lighter skater's velocity
... then find the time to travel 25 m

Answer 2

40/85 times the mas, so 85/40 times the speed.
Thus, 40/85 the time: 40/85 * 30 = ___ s