Bullet buries itself in a pendulum: how far does it swing?

[mrtkawa]

i need help for this problem
if anyone could solve this, it's wonderful

A 20g rifle bullet traveling 250m/s buries it self in a 3.8kg pendulum hanging on a 2.3m-long string. how far does the pendulum swing horizontally?

Physics 3rd edition Douglas C. Giancoli

 

[phucnv87]

Just using the law of conservation of momentum[/color]

 

[mrtkawa]

thanks i got it