Not quite. Momentum and energy are indeed conserved. however, momentum is a vector, not a scalar, and has direction. Take the extreme of a car hitting a tree. If the car bounces off the tree at the same velocity as it hit the tree, do you think the car imparted no force to the tree?
The tree had to first decelerate the car to zero, then accelerate the car in the opposite direction. If in the collision the car just stops, it only had to decelerate the car. The conservation of momentum states that the momentum changes of each object in a collision are equal in magnitude and opposite in direction.
No, you guys are still confusing total energy and force. You're not creating energy by bouncing something off the armor, but you do require more force to reverse it's direction. It requires force to make something change direction. Thus, you must apply more force to reverse an object than to stop it (assuming the time of application of the force is the same). That force is applied by the armor/body. However, as I said in my previous post, what really matters is how much 1) time and 2) area this force is applied over.
Your logic is indeed false. First, it is arriving with a velocity and an associated momentum, not a force. Force is imparted on the bullet to change it's momentum and direction. Thus if it's really bouncing in the opposite direction, then twice the energy is required to stop it is imparted to the armor. See the sarcastic reply under yours for why this is unlikely the case. Most fo the time it would likely be deflecting off, requiring less energy than that required to stop the bullet.
However, this still tells you nothing of the force. The peak force imparted to the bullet will be determined by the interaction of the bullet with the armor and contact time of the bullet with the armor.
However, it's not even the force that you care about, it's the pressure imparted to the tissue. This will be determined by how the force is distributed over the armor. The force will be much greater if it's distributed over a 1 cm^2 area as opposed to a 1 m^2 area.
To sum up, it's complicated and you can't draw conclusions of the performance of this armor by whether it "bounces off" or not.
Slashdot Mirror
...and thus inversely proportional to testicular mass.
Actually that one was worked out in Myth Busters. A brisk walk was deemed best under most rain conditions.
Not quite. Momentum and energy are indeed conserved. however, momentum is a vector, not a scalar, and has direction. Take the extreme of a car hitting a tree. If the car bounces off the tree at the same velocity as it hit the tree, do you think the car imparted no force to the tree? The tree had to first decelerate the car to zero, then accelerate the car in the opposite direction. If in the collision the car just stops, it only had to decelerate the car. The conservation of momentum states that the momentum changes of each object in a collision are equal in magnitude and opposite in direction.
No, you guys are still confusing total energy and force. You're not creating energy by bouncing something off the armor, but you do require more force to reverse it's direction. It requires force to make something change direction. Thus, you must apply more force to reverse an object than to stop it (assuming the time of application of the force is the same). That force is applied by the armor/body. However, as I said in my previous post, what really matters is how much 1) time and 2) area this force is applied over.
Your logic is indeed false. First, it is arriving with a velocity and an associated momentum, not a force. Force is imparted on the bullet to change it's momentum and direction. Thus if it's really bouncing in the opposite direction, then twice the energy is required to stop it is imparted to the armor. See the sarcastic reply under yours for why this is unlikely the case. Most fo the time it would likely be deflecting off, requiring less energy than that required to stop the bullet. However, this still tells you nothing of the force. The peak force imparted to the bullet will be determined by the interaction of the bullet with the armor and contact time of the bullet with the armor. However, it's not even the force that you care about, it's the pressure imparted to the tissue. This will be determined by how the force is distributed over the armor. The force will be much greater if it's distributed over a 1 cm^2 area as opposed to a 1 m^2 area. To sum up, it's complicated and you can't draw conclusions of the performance of this armor by whether it "bounces off" or not.