.Calculating Time for .22 Rifle Bullet to Stop in Soft Wood

[theonerealazn]

Ok, so here's my question:

A .22 rifle bullet, traveling at 350 m/s, strikes a block of soft wood, which it penetrates to a depth of 0.130 m. The block of wood is clamped in place and doesn't move. The mass of the bullet is 1.80 g. Assume a constant retarding force.

I know this has already been posted in another thread, but i have an additional question that i can't get.
1. How much time is required for the bullet to stop?
i tried 0.130m/350m/s and got .00037143 seconds as an answer. This was not correct. Any suggestions on what to do?

I already know that the wood exerts 848 N on the bullet

 

[steve23063]

F=ma where F=net force on the bullet=848N and m=mass of the bullet=.0018kg. Find a

Vf=Vi+a*t
Vf, Vi and a are all known at this point. Solve for time.

Your answer is close. You are off by a factor of 2.