MOMENTUM, VEOCITY, [PHYSICS} please helppp??=]?

Question

object 1, mass 5.0 g, moves at a speed of 20 cm/s. It collides with object 2, with mass 10.0 g, moving at 12 cm/s in the same direction. After the collision, object 1 continues with a speed of 8.0 cm/s in the same direction.

How do you find the momentum and velocity of object 2 after the collision???

thanks. :]

Answer 1

momentum conservation >>
before = after
m1u1+m2u2 = m1v1+m2v2
0.005*0.20+0.010*0.12 = 0.005*0.08+m2v2
m2v2 = momentum of 2 after = 18*10^-4 kg-m/s = 180 g-cm/s
v2 = 18 cm/s

Answer 2

(10.0 g)v + (5.0 g)(8.0 cm/s) = (5.0 g)(20 cm/s) + (10.0 g)(12 cm/s)

v = (100 gcm/s + 120 gcm/s - 40 gcm/s) / 10.0 g

v = 18 cm/s