Is the Calculation of Force on a Bullet in a Rifle Barrel Correct?

[eb41490]

help on homework please...force

hey, i don't know if what i did for this question is correct, because the equation i found in my textbook may not be the right one to use.

A 5.0g bullet leaves the muzzle of a rifle with a speed of 320m/s. What force (assumed constant) is exerted on the bullet while it is traveling down the .82m-long barrel of the rifle?

i used the equation:
(m(v^2)) / 2d =F

(.005kg*(320m/s)^2 )/ (2*.82m) =F
F= 312.2N

Is this close to being correct?

 

[BerryBoy]

There are two ways to do this problem, the easiest is with energy (which is what I assume you did), I deleted a post doing the other way

Take work done on the bullet and equate to kinetic energy:

$$Fd = \frac{1}{2}mv^2$$
$$F = \frac{mv^2}{2d}$$

Your answer looks good to me

 

[ogb p]

I'm not sure if the force would be constant or if there would be a change in force as the bullet travels down the barrel. If you could clarify that for me, that would be great. Also, it would be helpful if you could provide more information about the specific problem you need help with so I can provide a more accurate response. Thank you.