# Homework Help: Velocity problem

1. Oct 6, 2009

1. The problem statement, all variables and given/known data

A bullet with a mass of 1.5g is fired from a gun with an initial force of 500 N over 20m
Find the initial velocity of the bullet as it leaves the muzzle.

2. Relevant equations

m=1.5g, F=500N, d=20m

3. The attempt at a solution

i cant seem to find the equation that would fit this problem any help or advice would be greatly appreciated

2. Oct 6, 2009

### Delphi51

Given the force, you can find the acceleration easily.
Have you got an accelerated motion formula with no t in it?
There is one with just velocity, acceleration and distance that just kills this kind of question.

If you don't have it, I suggest you find the time it takes to travel the 20 m long gun barrel (wow, long one!). Then you can use the usual accelerated motion formulas to get the speed at that time.

3. Oct 6, 2009

i need to find the initial velocity, there is no acceleration involved i just cant find any equation that would work

the best one ive found is v^2= (kx^2)/m but i cant find k from the info i have so im stuck. if i had k then i could solve this problem.

4. Oct 6, 2009

### Delphi51

The question is poorly worded - it wants the velocity when the bullet leaves the gun and that would better be called the final velocity.
It most certainly will accelerate with 500 N applied to .0015 kg.

v^2= (kx^2)/m looks like a spring formula. You don't have a spring here.