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## Homework Statement

a bullet of mass 0.005kg traveling at 120m/s hits a block at rest that falls and compresses a spring (k=99n/m) to a maximum compression of 0.121m what is the mass of the block? (solve using momentum)

m1=0.005kg

m2=?

v1=120m/s

v`=?

k=99n/m

x=0.121m

## Homework Equations

m1v1=(m1+m2)v`

Ee=Ek

Et=Et`

## The Attempt at a Solution

attempt one

Ee=Ek

1/2kx^2=1/2m1v^2

v=squareroot((kx^2)/m1)

v=17m/s

m1v1=(m1+m2)v`

0.005(120)= (0.005+ m2)17

0.005(120)/17=(0.005+ m2)

0.03529=(0.005+ m2)

0.03529-0.005=m2

0.030=m2

I got it wrong and my teacher will not tell me the answer I can't see were i went wrong