Home Forums Reloading Big Game Rifles TTSX and E-tip.

I know this shoot a steel target and then walk up and touch the target and it will not burn you....

My point is that F=ma and kinetic energy = 1/2 mass x velocity squared. Both are dependent on the mass and change in velocity of the object. So, while they are not directly proportional, the force and the energy of a bullet do go hand in hand.

Net Force is Mass in kilograms time velocity in meters per secound not squared. 1 Newton force is 1 kilogram at 1 meter per secound = 1 Newton Force



Fnet = m * a


http://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/newtlaws/u2l3a.html

Cut and pasted from the URL you provided:

"The definition of the standard metric unit of force is stated by the above equation. One Newton is defined as the amount of force required to give a 1-kg mass an acceleration of 1 m/s/s."

an acceleration of 1 meter per second per second is also expressed as one meter per second squared.

E.G. the acceleration of gravity is 32 feet per second squared. In other words, an object dropped in a vacuum (without air resistance) will be going 32 fps after one second, 64fps after 2 seconds, etc.

Correct southtexas.

jwp,
f=ma means that force equals mass times acceleration. Acceleration is meters per seconds squared...

Answer: Fnet = 10 N

Fnet = m � a
Fnet = (2 kg) � (5 m/s/s)

Fnet = 10 N


Not squared

Look at the tutorial and the answers


http://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/newtlaws/u2l3a.html

Answer: a = 5 m/s/s

a = Fnet / m
a = (20 N) / (4 kg)

a = 5 m/s/s

http://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/newtlaws/u2l3a.html

Your answer of "a = 5 m/s/s" is 5 meters per second per second, which is mathematically equivalent to meters per second squared.

Look at the very first formula (in red) for "a" on your website. It says a=m/s2.

VELOCITY is expressed in units of length per unit time (feet per second or meters per second)

ACCELERATION is expressed in units of length per unit time squared (feet per second squared or meters per second squared)

Don't think Newtons laws have changed since I was in engineering school.

LOL, I was a physics major for a portion of my university education, and am quite familiar with these formulas and what the mean and represent.

jwp,
If you want, we can just agree to disagree

Jordan: So I assume Sir Isaac hasn't changed his mind?

Nope not yet. I guess he has yet to be convinced by some of the rising generation that he is old school and that the world has changed

Physics defines or describes things mathematically - at least that is how I view it. And, yes, it can be very useful for calculating what will happen - assuming "we" can figure out every pertinent detail beforehand. Obviously, as with sending rockets into space, there are things we can't know before the experimental first attempts. That's because we don't always have every principle applied correctly.

I think the same applies to what we sometimes see with projectiles fired from sporting weapons. Does physics apply? Sure it does. Do we have every factor identified so that we can define it? I'm not so sure about that; in fact, pretty sure we don't - at least not in simple enough ways for laymen to understand.

Does a bullet burn through steel? I don't think so. (It looks a lot like a rock dropped into stiff mud to me, and rocks don't burn holes in mud.) Could heat make a hole in a very small concentrated area and then dissapate or be absorb into surround matter? Does that seem to happen in other examples? Hmmm, a plasma cutter comes to mind; so to, a spot welder. So, maybe, but still, I don't think it is heat. It seems to me that the energy required could be quantified in such a way as to prove the negative. No?

You can approach this stuff two ways. You can calculate the theory and then prove it (or not) through experiementation, or you can try things and then attempt to describe them mathematically. I think we are doing the latter, attempting to describe what is observed. I don't think that has been done satisfactorily.

Nope. You're forgetting about the cube-square ratio. The volume (mass/weight) of a sphere goes up as the cube of the radius, while the surface area only goes up by the square of the radius. So, larger balls fly better, with higher BC.

This is true. Thanks for pointing that out.

All I know is, I see a big splatter mark on a steel plate when shot with the fmj 223 bullets we use, and it is definately the steel that is splattered. I also see lead tipped bullets disentegrate when shot at velocities approaching 4400 fps. There is no doubt that this happens. You can see it when it happens. I have a steel target manufacturer that says that the biggest problem is the heat generated by the bullet strike. It will be hard to convince me that there is not considerable heat generated when a bullet strikes a steel plate and all that energy is dissapated right now and in a very small area. The energy has to go somewhere.

A-36 1" thick Steel target





AR-500 1/2" thick shot with the same rifle and bullets






If the bullets heat were melting through then both targets would look the same...

Thank you. I understand real examples better than numbers squared or cubed and that makes perfect sense. I have a pic somewhere of what a 535 grain .458 bullet did(n't do) to a 1/4" steel plate while a puny little 25 grain 17 cal bullet zipped. As I recall, the divot from the big bullet was warm (it stretched the steel) while the tiny, clean hole was nil for warmth.