# Physics question for AO: Why do bounces hurt more than breaks?

• 03-27-2013, 07:13 AM
Lohman446
Physics question for AO: Why do bounces hurt more than breaks?
I have a couple guesses as to why this is having to do with energy but they are simply guesses. Since AO has always prided itself on being the forum with answers that are based in science I figure the question is a good one for here.
• 03-27-2013, 07:53 AM
cougar20th
My guess has always been that bounces hurt more because the shell does not break so it doesn't dissipate the energy as a shell breaking would do.

Similar to how newer car crush and dissipate the energy while older cars don't.
• 03-27-2013, 07:53 AM
OPBN
Wouldnt it have to do with the mass/energy being spread out vs concentrated on one point? When it bounces, all the force is behind the point it hits. When it breaks, the mass spreads out and looses momentum? Similiar to how they design cars now days to actually crush a certain way rather than building the frames so rigid that they bounce off. The crushing absorbs the impact rather than repelling it.

Edit: Cougar beat me to it.
• 03-27-2013, 07:57 AM
livebrando
Monster balls bounce more than others :nono:
• 03-27-2013, 08:17 AM
BTAutoMag
so do marbles
• 03-27-2013, 08:45 AM
Nobody
if you think about how a ball breaks, its not at the point of impact, but the sides of the shell. the PoI is static, its not moving cause it has come against a solid object(you). so think of the shock wave or ripple coming off you, then you have the momentum of the ball still traveling(the ass still trying to catch up with the nose). so that wave is meeting in the middle with the kinetic energy and the weakest point is the sides of the ball.

so take that into consideration that bounces may have thinker shells, or just are in the curved path so it glances, or whatever. it just is a fact that bounces hurt more and that you should get better cover or learn to stick in better.
• 03-27-2013, 08:49 AM
OPBN
Bounces may hurt more, but oddly I find that breaks tend to leave bigger welts. Why is that?
• 03-27-2013, 09:46 AM
Dayspring
Tom and company did a test on this in the deep blue section a while back. Lemme see if I can find it.
• 03-27-2013, 09:55 AM
Dayspring
• 03-27-2013, 10:26 AM
captian pinky
it has to do with impulse and momentum equations basically it hurts more because of the bounce. the bounce causes a greater difference in acceleration, and requires a greater force

found this and it kind of explains it. might be able to find a better explanation in my book but ill have to look later.

https://thescienceclassroom.wikispaces.com/Momentum
• 03-27-2013, 11:28 AM
Cokrkilr
The bounce theory you guys are saying is correct, its all about transfer of energy.

The welt thing, this is just a theory. But when I get a break on bare skin, like forearms or calves, I usually have a larger welt than where my Jersey or shorts are. Aside from the clothing taking some of the energy (the Jersey is minimal because its so light) I think it may also have something to do with the shell creating micro cuts in your skin and irritating it more. But that being said, I've taken shots to the back that bled, and a Bunker double in the sternum that left a scar for about 2 years (tournament w/ 300 velocity limit, about a foot from the barrel to my chest) funny thing was it was literally two shots over eachother, dead center in the chest, looked like I had 3 nipples for a long time... haha

Id leave that open to skin type more than anything
• 03-27-2013, 11:56 AM
SeeK
The degree of welt size is more dependent upon the fat layer behind the skin since you can see the difference in welts on more muscular areas like the legs/arms, the belly and the head.

You will also notice that new welts are almost always a ring shape because the skin that is at the edges of the paintball shell would stretch the most. Look at stop motion pictures of a drop of water to see the wave effect of energy dispersion.
• 03-27-2013, 09:47 PM
Sniper Steve
I would say breaks hurt more because you have to walk back to the flag and the more walking you do the more tired your legs are at the end of the day.;)
• 03-27-2013, 11:41 PM
thrasher_565
i would think because the energy was not azorb fully. that's my guess. a slow mo shot would probably answerer your question.
• 03-29-2013, 12:17 AM
koleah
Basically, it comes down to an elastic collision versus an inelastic collision (if you want to actually go look those up).

When a ball breaks, your skin is only providing enough energy to stop the ball. When it bounces, your skin is providing enough energy to stop the ball, reverse its direction, and send it back the other way.

Think about if someone pitches a baseball to you, and you bunt it so that it only goes a few feet. Think about how you would control the bat to make that bunt. That bat is your skin absorbing the energy of the ball.
Now think about if someone pitches you a baseball, and you smack it out of the park (which is basically just the ball bouncing off the bat REALLY hard). That bat is now your skin completely stopping and reversing the direction of the (paint)ball.

http://hyperphysics.phy-astr.gsu.edu/hbase/elacol.html
>"A perfectly elastic collision is defined as one in which there is no loss of kinetic energy in the collision. An inelastic collision is one in which part of the kinetic energy is changed to some other form of energy in the collision."
Also, when the ball breaks (inelastic collision), its using up the kinetic energy of the ball to overcome the integrity of the shell and send all the paint out in a splatter pattern, meaning less energy absorbed by your skin.
Because the bounce doesn't lose that shell-breaking-energy, there is more energy which has to be absorbed by your skin, resulting in higher pain.
• 03-29-2013, 01:09 PM
athomas
It was mentioned above in one of the posts. In order for a ball to bounce all of the momentum and kinetic energy in the moving ball has to be absorbed at the point of impact and redirected. All of the energy is felt at the point of impact. In a perfect world, the velocity of the redirection is directly proportional to the mass of the objects colliding and the velocity at which they collide. Since the person is so much larger than the paintball, all energy (less that absorbed by elasticity) ends up back at the paintball.

Now, given a ball that breaks, the energy at the point of impact is not the same. The paint that spreads out is redirected and never actually makes contact with the same point of contact as the front of the ball. All of the energy contained in that mass is not felt as part of the impact on the same spot as the front of the ball. It will be felt as part of the impact, but the impact area will now be larger due to the deflected paint and shell. If you average the same impact force over the larger area, the same energy dissipated over a larger area results in less force per area so it doesn't hurt quite so badly.

The ball breaking around the outer edge during impact causes the ring welt. There is much less energy at the ring, but confined to the sharper edge, much like the edge of a knife vs the back of a spoon.