Force Needed to Stop a Flying Bullet

IBdoomed

A bullet of mass 0.0025 kg moving at 470 m/s
impacts a large fixed block of wood and travels
6.2 cm before coming to rest.
Assuming that the deceleration of the bullet
is constant, find the force exerted by the wood
on the bullet.
Answer in units of kN

I know force= mass * acceleration but i don't know how the distance plays into the solution. Any kind of kinematics formula would be sufficiently helpful!

PeterO

Choose wisely from the sets of equations shown in the first two sections of this wikipedia posting.

http://en.wikipedia.org/wiki/Equations_of_motion

IBdoomed

i was trying to use v^2= u^2+2as
but the answer i am getting is wrong....
is there a different formula you suggest?

PeterO

That is certainly the one I would use.

Were you converting everything to metres and seconds?

This formula will only calculate the acceleration of course - you need at least one more step to get the force.

IBdoomed

nevermind. i was not converting my answer into kN.... thank you so much!