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.
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.
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