physics project for school, please give input

[bblaha]

check out my friends and i physics project involving finding the initial velocity of a bullet when fired from a gun this is just a rough draft/first trial. if oyu have any recommendations feel free to tell me, feel free topost as well, thanks for looking -brett blaha Ballistic Pendulum - YouTube our grade is largely determined by how many views we get so thanks for watching

 

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[seekandfind]

Hey bblaha I have seen you on here talking about your magnet fishing, I may try that someday. Thought I would let you know Harbor Freight has a low priced magnet out that supposedly will grab and hold up to 250 lbs.. This magnet lloks perfect has a handle to tie onto and should work well. Just info if your interested.HH

 

[Number9]

Do I understand this right?

Two different weight bullets fired at target at the same distance...
Measure the amount(travel) "swing" of the target to calculate the speed of the bullets at target...
By knowing the weight of both bullets.. you're able to calculate velocity by the energy it takes to move the weight of the target a certain distance.

...right?

 

[bblaha]

Do I understand this right?

Two different weight bullets fired at target at the same distance...
Measure the amount(travel) "swing" of the target to calculate the speed of the bullets at target...
By knowing the weight of both bullets.. you're able to calculate velocity by the energy it takes to move the weight of the target a certain distance.

...right?

Yes that is correct because all of the energy is transferred from the bullet into the wood

 

[bblaha]

Hey bblaha I have seen you on here talking about your magnet fishing, I may try that someday. Thought I would let you know Harbor Freight has a low priced magnet out that supposedly will grab and hold up to 250 lbs.. This magnet lloks perfect has a handle to tie onto and should work well. Just info if your interested.HH

I'll take a look at it thanks for letting me know

 

[TNGUNS]

Lots of variables in that one....If the hit is off center would totally wreck the results. The blocks would have to be exact in weight. Length of rope must be the same. The list goes on. Understand the concept, but tough. How much energy was expended in penetrating the block ( not sure if this would factor ). The energy lost in deforming the block would have to effect how much was then transferred into moving it.

Long story short...I work at shooting range and will be glad to help if ya need anything.

 

[Number9]

Yes that is correct because all of the energy is transferred from the bullet into the wood

Great!

Got a question...

Let's say...

You have two bullets... same weight... same velocity... same distance to target.
The only difference... one of the two bullets is larger in diameter than the other.

If both hit a target made of hardened steel, the target will move the same distance with both bullets.

But.. If the target is made of soft material... would it swing the same distance with either bullet?

The smaller diameter would travel further into the target because it would have less resistance or drag...
thus would give up it's energy over a longer travel and time through the soft target than the larger diameter bullet which would give up its energy sooner at a shorter distance...

Question... would the target move the same distance?

 

[bblaha]

Lots of variables in that one....If the hit is off center would totally wreck the results. The blocks would have to be exact in weight. Length of rope must be the same. The list goes on. Understand the concept, but tough. How much energy was expended in penetrating the block ( not sure if this would factor ). The energy lost in deforming the block would have to effect how much was then transferred into moving it.

Long story short...I work at shooting range and will be glad to help if ya need anything.

What do you thin a better way to set this up would be? All the wood was measured to be closely the same, and was set with a level from the same height. But what do you think I should do to get it to swing like a straight pendulum

 

[bblaha]

Great!

Got a question...

Let's say...

You have two bullets... same weight... same velocity... same distance to target.
The only difference... one of the two bullets is larger in diameter than the other.

If both hit a target made of hardened steel, the target will move the same distance with both bullets.

But.. If the target is made of soft material... would it swing the same distance with either bullet?

The smaller diameter would travel further into the target because it would have less resistance or drag...
thus would give up it's energy over a longer travel and time through the soft target than the larger diameter bullet which would give up its energy sooner at a shorter distance...

Question... would the target move the same distance?

The reason we used wood rather than metal was so that it would absorb the full energy and momentum of the bullet. Since it is an elastic collision all of the energy is transferred so the two bullets should move it the same if we set it up correctly, ours was done very messy though

 

[Frankn]

Well since I am practically deaf and there was no captioning I didn't get much from the flick. I have done a bit of gun repairing and moding in my time and I used an instrument that caught the shadow of the bullet as it left the barrel and about one foot further. It calculated the time and read out the speed. In your setup the amount of energy required to penetrate the wood is different from the amount of energy required to move WITH the wood. Did you take this into consideration? Frank

 

[Number9]

Have you thought about using a chronograph at the target to check your velocities?

 

[ivan salis]

humm if the gunpowder load is the same and the bullet caliber is the same --thus same amount of force used to propel both of the bullets --the heavier bullet since it has more "mass" should be a bit slower but being heavier it should have more kentic energy (impact force) -but the lighter bullet being a flatter shooter -- should have a bit more speed going for it --now which will have more of a "impact"/ transfer of energy on a soft wooden target block thus causing more "swing" ? -- the distance travelled before it hits the target is a big factor since at longer range the heavier bullet will rapidly bleeding off speed / energy . -- lighter bullets are flatter shooting at long range . the mass of heavier bullets causes them to slow down and thus drop more quickly.

thus short range vs long range the test results could vary a good bit.

 

[Number9]

Ivan.. I think his project was just a way to calculate velocity of a bullet of a known weight based on how far the target would swing?

I guess my question wasn't understood?

Two bullets, same weight.
Hits a soft target at the same velocity.
Both would have the same kinetic energy.
So the target would swing the same with either bullet.

But... If one bullet is bigger in diameter, it wouldn't penetrate as deep as a same weight bullet that's smaller in diameter traveling at the same velocity.
Same amount of energy hitting the target... but the target would swing further with the larger diameter bullet.
The difference is "time" of each penetration. You couldn't measure the difference in your back yard!
The larger diameter bullet would give-up it's energy quicker by not penetrating as deep.

Oh well.. I'll stop here... I need to get back to arguing with Kuger! LOL!!!

 

[Frankn]

Some info input.
I have seen the test targets used to compare the .45ACP and the 9MM Luger by the Army. It was an App. 1/4 " steel plate shot at close range. The .45 put one hell of a bulge in it, but the 9MM penetrated it.
I ran some tests on .22/250 ammo loaded for 4000FPS, which is normal. The target was a piece of armor plate that is used in the hummv upgrade. app. one out of every three shots from 50 yards penetrated it. The copper jacket stayed in the armor plate, but the lead core went thru. The other two were in the plate and just shy of penetration. If I had loaded to 4300 FPS all would have probably penetrated and there ic commercially loaded .22/250 ammo available. Frank

 

[Arizona Bob]

You should try to control ALL the variables that you can. You may want to do this on a gun range. It looked to me in the second shot, that the barrel of the gun was a couple of inches closer to the target when fired. Unequal distances give different results. I would suggest locking the gun into a shooters stand, after measuring the distance to the target. Also, you probably haven't covered angular momentum/forces in class yet, but if your shot is off-center, your force is split between (left/right) rotation of the target as well as swing. Also, when you shoot at the same block of wood, the mass of the wood has changed after the first shot- it is lighter due to the wood that is ejected as a result of the first bullet. You may want to use a new piece of wood for each shot. Good experiment & video!

 

[Number9]

 

[bblaha]

Got a 92!