BellaRobberts
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Formula for calculating impact. Science project of impact and penetration of a bullet.

Postby BellaRobberts » Wed Jun 19, 2019 7:57 am

Hello there,

I am testing the penetration and impact of a bullet across a 50m distance. I need help with the science behind it.

The bullets all differ in weight, which is why I am testing the penetration and force of impact.

Help!

norman40
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Re: Formula for calculating impact. Science project of impact and penetration of a bullet.

Postby norman40 » Wed Jun 19, 2019 1:44 pm

Hi BellaRobberts,

This forum is intended for students, parents, and teachers working on K-12 science projects. If your question is related to a science project, please post some details such as your hypothesis, research question or experimental plan. If you are looking for help with homework or general science discussions there are other sites that should be able to answer your question.

A. Norman

BellaRobberts
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Re: Formula for calculating impact. Science project of impact and penetration of a bullet.

Postby BellaRobberts » Thu Jun 20, 2019 10:38 pm

Apologies.

I am doing a science fair project on the ballistics of a bullet, with specific focus on the level of penetration into a wooden block, with different weighted projectiles.

We are testing 139,145 and 162 gr bullet points, by firing into wooden blocks at a 50m distance.

Our rifle caliber is a 7mm Remington Magnum. All bullets are loaded with 85gr of propellant.

Our hypothesis is that the heaviest bullet will cause the largest penetrating distance, due to the force behind is.

My question is, how can I prove this scientifically?

Thank you in advance. :idea:

AmyCowen
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Re: Formula for calculating impact. Science project of impact and penetration of a bullet.

Postby AmyCowen » Fri Jun 21, 2019 2:45 pm

Is this a student science project you are doing?

Please note that experiments with firearms are discouraged and or banned at most science fairs.

Science Buddies follows ISEF rules and local laws and regulations when it comes to firearms and encourages all parties to maintain public and personal safety at all times. ISEF rules are outlined here: https://student.societyforscience.org/hazardous-chemicals-activities-or-devices

D. Firearms and Explosives
The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), along with state agencies, regulates the purchase and use of firearms and explosives. A firearm is defined as a small arms weapon from which a projectile is fired by gunpowder. An explosive is any chemical compound, mixture or device, the primary purpose of which is to function by explosion. Explosives include, but are not limited to, dynamite, black powder, pellet powder, detonators, and igniters.

The purchase of a firearm by a minor is generally unlawful. The use of a firearm, without proper state certification, is illegal. Students should check the training and certification requirements of individual states and countries.

* Projects involving firearms and explosives are allowable when conducted with the direct supervision of a Designated Supervisor and when in compliance with all federal, state and local laws.
* A fully assembled rocket motor, reload kit or propellant modules containing more than 62.5 grams of propellant are subject to the permitting, storage and other requirements of federal explosive laws and regulations.
* Potato guns and paintball guns are not firearms unless they are intended to be used as weapons. However, they must be treated as hazardous devices.


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BellaRobberts
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Re: Formula for calculating impact. Science project of impact and penetration of a bullet.

Postby BellaRobberts » Fri Jun 21, 2019 11:18 pm

Hi,

A student is doing the project.

In South Africa, we are allowed to do projects on rifles and my student is an avid hunter. It's not frowned upon in South Africa. As long as a licensed firearm handler oversees all activity.

My student has been loading his own ammunition and hunting since he was 7 years old, under supervision, obviously.

But, I would really appriciate an answer or could you possibly suggest alternative webpages or forums I can visit?

Kind regards.

norman40
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Re: Formula for calculating impact. Science project of impact and penetration of a bullet.

Postby norman40 » Mon Jun 24, 2019 3:26 pm

Hi BellaRobberts,

The project you've proposed seems dangerous for a middle school science fair. But it appears from your most recent post that the work will be supervised by someone with firearms safety expertise. Hopefully all safety concerns will be addressed if you move forward with this project.

Regarding the question from your previous post, once you've formulated a hypothesis the next step is to design an experiment to test it. And you've outlined a reasonable experiment for that purpose. After properly conducting the experiment you will have results that support or do not support your hypothesis.

Science Buddies has an excellent science fair project guide that explains the hypothesis and experimental steps as well as all of the other elements of a project. The guide is available here:

https://www.sciencebuddies.org/science- ... ience-fair

And the sections on the hypothesis and experiments are here:

https://www.sciencebuddies.org/science- ... hypothesis

https://www.sciencebuddies.org/science- ... procedures

Your experimental results can be interpreted based on the kinetic energy of the bullets. A moving object has kinetic energy proportional to the mass and to the square of the velocity of the object. At equal velocity a bullet with greater mass will have more kinetic energy than one with less mass. Higher kinetic energy should translate into more penetration by the bullet unless other factors inhibit the penetration.

More details about kinetic energy are available here:

http://hyperphysics.phy-astr.gsu.edu/hbase/ke.html

I hope this helps. Please ask again if you have more questions.

A. Norman

BellaRobberts
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Re: Formula for calculating impact. Science project of impact and penetration of a bullet.

Postby BellaRobberts » Mon Jun 24, 2019 10:58 pm

Thank you so much for answering my question.

I assure you all test are done in a safe and controlled environment, under supervision from licenced firearm handlers. No live ammunition will be used during the sceince fair or will be present.

I used the formula: 0.5 x M x V^2 to calculate the impact. Is this correct?

Thank you.
I eagerly await your response.

norman40
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Re: Formula for calculating impact. Science project of impact and penetration of a bullet.

Postby norman40 » Tue Jun 25, 2019 2:37 pm

Hi BellaRobberts,

Yes, that is the correct equation for kinetic energy.

I hope this helps. Please ask again if you have more questions.

A. Norman

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Re: Formula for calculating impact. Science project of impact and penetration of a bullet.

Postby bfinio » Fri Jun 28, 2019 9:36 am

Hi BellaRobberts,

I'm going to chime into this discussion with a few more suggestions in addition to A. Norman's. Be careful when using words like "force," "energy," and "impact" in a physics project. We might use them somewhat interchangeably in everyday speech, but in physics they have specific definitions (and units) and are not the same thing. So, for example, you could say KE = 1/2*m*v^2 is the formula you use to calculate the kinetic energy of the bullet (which you would expect to have a correlation with the penetration distance), but it isn't correct to say you use that formula to "calculate the impact." Your original question mentioned "force of impact." Force has a specific definition related to Newton's 2nd law of motion (force = mass * acceleration, or F=ma) which is a different equation, and would require different information to calculate. So if you actually want to calculate "the force," I could explain that in another post.

I'm not sure how it works in South Africa, but in the US most students would only get a very brief exposure to this in middle school, and then take physics in high school and learn all the more formal definitions and equations for things like velocity, acceleration, force, energy, etc. So, it's a bit much to explain all of it from scratch in a forum post. Here's another good online physics site, in addition to the Hyperphysics site A. Normal linked - the first two parts (1-D Kinematics and Newton's Laws) will be useful:

https://www.physicsclassroom.com/class

Hope that helps,

Ben


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