Solving Velocity Problem: Initial Force 500N & Mass 1.5g Over 20m

[meadman]

Homework Statement

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.

Homework Equations

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

The Attempt at a Solution

i can't seem to find the equation that would fit this problem any help or advice would be greatly appreciated

 

[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.

 

[meadman]

i need to find the initial velocity, there is no acceleration involved i just can't find any equation that would work

the best one I've found is v^2= (kx^2)/m but i can't find k from the info i have so I am stuck. if i had k then i could solve this problem.

 

[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.