Kinetic Energy vs. Momentum in Projectile collisions

In summary, kinetic energy and momentum both play important roles in determining the destructive force of a projectile in a collision. While kinetic energy is responsible for the amount of energy released, momentum determines the force applied to the target and can also contribute to the damage done.
  • #1
gearhead
31
0
I'm trying to figure out the role that kinetic energy and momentum play in projectile collisions. there are two cases: 1.) when the projectile becomes completely embedded in the target and 2.)When the projectile completely passes through the target and flys out the other end.
If the collision is completely inelastic in situation 1, then wouldn't the impact force just be impulse? given by the equation: Force*delta(t)=change in momentum. If this is true, then isn't the destructive force a projectile related solely to it's momentum and not it's kinetic energy? The only situation i see where having a high kinetic and low mometum is better than having really high momentum and low energy, is situation 2.

I shoot bow and arrow, and my bow shoots a 25.7gram arrow 46.4m/sec, giving it a momentum of 1.19 kg*m/s. The energy is only 27.66J. Now compare this with a .22lr: 2.6 grams moving @ 330m/sec., which gives it only 0.858kg*m/s. But it has an energy of 141.5J.
Although my intuition tells me the bullet will do more damage, i don't understand why.
 
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  • #2
Is it the higher energy or momentum? The destructive force of a projectile is related to both its kinetic energy and momentum. In a collision, the kinetic energy of the projectile is converted to potential energy and is then dissipated in the form of heat, sound, and other forms of energy. This energy is ultimately responsible for the damage done. However, the momentum of the projectile also plays a role. Momentum determines how much force is being applied to the target and can have an effect on its structural integrity. Therefore, in the case of the bow and arrow and the .22lr, the higher energy of the .22lr will likely result in more damage due to the greater amount of energy that is released upon impact.
 

Related to Kinetic Energy vs. Momentum in Projectile collisions

1. What is the difference between kinetic energy and momentum in a projectile collision?

Kinetic energy is the energy an object possesses due to its motion, while momentum is the measure of an object's motion. In a projectile collision, both kinetic energy and momentum are conserved. However, kinetic energy takes into account the object's speed and mass, while momentum only considers the object's mass and velocity.

2. Which one is more important in a projectile collision, kinetic energy or momentum?

It depends on the specific scenario. In general, both kinetic energy and momentum are important in a projectile collision. However, if the objects involved have significantly different masses, momentum may play a larger role. On the other hand, if the objects have similar masses but different speeds, kinetic energy may be more important.

3. How are kinetic energy and momentum related in a projectile collision?

Kinetic energy and momentum are related because both are measures of an object's motion. In a projectile collision, the kinetic energy and momentum of the objects before and after the collision must be equal, as they are conserved quantities. This means that if one increases, the other must decrease to maintain the overall conservation.

4. Can an object have a high kinetic energy but low momentum in a projectile collision?

Yes, an object can have a high kinetic energy but low momentum in a projectile collision. This can happen when the object has a high speed but a relatively small mass. In this case, the object's kinetic energy will be high due to its speed, but its momentum will be low because momentum also takes into account the object's mass.

5. How does the angle of a projectile affect kinetic energy and momentum in a collision?

The angle of a projectile can affect both kinetic energy and momentum in a collision. When a projectile collides at an angle, some of its kinetic energy and momentum will be transferred to the object it collides with. The angle of the collision can determine how much energy and momentum is transferred in each direction, and can also affect the final direction and speed of the objects after the collision.

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