What Equation?

[Draygon_Phly]

Hi! I would like to know what equation I would use to figure out this question and why?

A 10-gram bullet is fired into a 3.0-kilograme block, given that the block a velocity of 30 cm/sec. With what velocity was the bullet fired?

Thank you for your answer. [?]

[Chen]

The conservation of momentum:
m_1v_1 + m_2v_2 = m_1u_1 + m_1u_2
So that:
m_ - mass of each object
v_ - velocity of each object before impact
u_ - velocity of each object after impact

Do you need more help or can you figure this out yourself now? [:)]

[Draygon_Phly]

thanx I can figure it out from here.[:)]