Calculating Bullet Velocity using Frictional Force and Block Displacement

[runningirl]

Homework Statement

You have been asked to determine the velocity with which a certain rifle fires its 2.0 g bullets. You are limited in equipment and so decide to set up the following experiment. You fire the bullet into a 0.50 kg block of wood which is resting on a tabletop. The bullet lodges in the bullet and the block slides 0.36 m across the tabletop before coming to a stop. You then determine that the frictional force between the block and the tabletop is 1.4 N. Use these data to determine the velocity of the bullet.

Homework Equations

f=ma
j=Fave(t)
P=m(v)
d=(Vf^2-Vo^2)/2a

The Attempt at a Solution

so i thought i could find the acceleration of the block by doing:
2.5(a)=1.4
a=.56 m/s/s

d=(Vf^2-Vo^2)/2a

.36=v^2/.56
v=.45 m/s?

 

[issacnewton]

mass of bullet is 2 g and that of block is 0.5 kg...so mass of the bullet would be 0.002 kg
you made mistake while adding masses