How Is Momentum Conserved in a Bullet and Ballistic Pendulum Collision?

[stupif]

1. a 7g bullet is fired into a 1.5kg ballistic pendulum. the bullet emerges from the block with a speed of 200m/s, and the block rises to a maximun height of 12cm. find the initial speed of the bullet and the kinetic energy lost of the bullet.
answer: 528m/s, 835.7j
2. mu+ mu = mv + mv
0.007u + 1.5(0)= 0.007(200) + 1.5kg(v)
how to know the final velocity of ballistic pendulum?? help me...please...
thank you

 

[rock.freak667]

The pendulum's max height is 12cm, so its KE at the collision = PE at 12cm.

so 0.5mv²=mg(0.12).

 

[stupif]

i got it...thank you very much~

 

[stupif]

https://www.physicsforums.com/showthread.php?t=519410

can you help me this question?