Momentum transfer from a transiting bullet

AI Thread Summary
The discussion clarifies the difference between momentum and energy in the context of a bullet's impact. It emphasizes that the energy transferred during the impact is calculated by the change in kinetic energy, represented by the formula 1/2mU^2 - 1/2mV^2. It also points out that knowing the energy or momentum lost by the bullet does not provide the force applied to the target without additional information on time or distance. The impact force varies significantly depending on the target material, illustrating that the same energy loss can result in different force experiences. Understanding these concepts is crucial for accurate analysis of ballistic impacts.
wirenut67
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Well the energy which it transfers, assuming it's all given in heat/other energy to the target is it's loss in Kinetic Energy;

\frac{1}{2}mU^2 - \frac{1}{2}mV^2

where U is it's initial speed and V is it's final speed after the impact, is that what you're looking for?
 
You appear to be confused between "momentum" and "energy". ft-lbs is a measure of energy, NOT force. Also, knowing how much energy or momentum the bullet lost will NOT tell you the "force applied to the target". you would also need to know either the time or the distance in which the bullet lost momentum or energy. Energy is average force times distance. And "distance" depends upon the substance the target is made of. A person dropping, from a given height, onto a matress will lose exactly the same momentum and energy as a person dropping from the same height onto a steel plate but the force experienced will be a lot less.
 
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