(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The spring of a spring gun has force constant k = 400 and negligible mass. The spring is compressed 6.00 and a ball with mass 0.0300 is placed in the horizontal barrel against the compressed spring. The spring is then released, and the ball is propelled out the barrel of the gun. The barrel is 6.00 long, so the ball leaves the barrel at the same point that it loses contact with the spring. The gun is held so the barrel is horizontal.

I found the velocity as it leaves the barrel as 6.93 m/s

Then it asks:Calculate the speed of the ball as it leaves the barrel if a constant resisting force of 6.00 N acts on the ball as it moves along the barrel.

I got the 4.9 as the right answer.

Then:For the situation in part B, at what position along the barrel does the ball have the greatest speed? (In this case, the maximum speed does not occur at the end of the barrel.)

And:What is that greatest speed?

2. Relevant equations

F = -kx

W = 1/2kx^{2}

K = 1/2mv^{2}

3. The attempt at a solution

For finding the first velocity, I used W= 1/2kx^{2}

where x = .06 m, and got it to be .72 J.

Then I set it to 1/2mv^{2}and got 6.93 m/s, which was right.

For part B, where a 6 N force acts against the bullet I found the work of the force with W = F*D = 6*.06 m = .36

Then I subtracted .36 from .72, which was .36, and set .36 = 1/2mv^{2}, and found the velocity to be 4.9, which was right.

For finding the position along the barrel I tried setting .36 = 1/2kx^{2}, and solving for x, but that didn't work, and without that I can't find the last velocity its asking for. Probably a simple mistake but I can't seem to find where, any ideas?? Thanks for any help.

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# Homework Help: Spring gun

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