Kinetic energy, size of object, and force applied

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Discussion Overview

The discussion revolves around the relationship between kinetic energy, size, and force applied by bullets of different weights and velocities. Participants explore how these factors influence the interaction of bullets with targets, particularly in terms of momentum and energy transfer.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether the size and weight of two bullets with the same kinetic energy affect their performance against targets, noting that a larger, slower bullet seems to impart more force than a faster, lighter bullet.
  • Another participant suggests that the faster bullet may not transfer all its energy to the target due to its ability to pass through it, implying that energy transfer is not solely dependent on kinetic energy values.
  • A third participant introduces the concept of momentum, stating that the heavier, slower bullet has more momentum, which may be relevant for moving or tilting the target, while energy is more related to damage or deformation.
  • A later reply prompts a participant to consider calculating kinetic energy and momentum to further explore the question, indicating that mathematical analysis could clarify the discussion.

Areas of Agreement / Disagreement

Participants express differing views on the significance of kinetic energy versus momentum in the context of bullet performance against targets. No consensus is reached regarding the implications of these factors.

Contextual Notes

Participants reference specific bullet characteristics and their effects on target interaction, but the discussion remains informal and lacks rigorous experimental validation. Assumptions about energy transfer and target interaction are not fully explored.

Skeet_man
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Kinda looking to confirm what I already suspect.

All things being equal, if two objects have the same kinetic energy, does the fact that one is larger and heavier than the other (although at a slower velocity) mean anything?

Specifically when comparing bullets. One bullet .451" in diameter, 230 grains in weight, traveling at 880 feet per second. Second bullet .356" in diameter, 124 grains in weight, traveling 1200fps. Both bullets have 396 ft/lb of kinetic energy. However, in a somewhat ad-hoc comparison against targets, the larger slower bullet is ostensibly being shown to impart more force on the target, causing it to tip over, whereas the faster lighter bullet fails to do so.

To my mind, at least in this instance, ft/lb is ft/lb.
 
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Skeet_man said:
All things being equal, if two objects have the same kinetic energy, does the fact that one is larger and heavier than the other (although at a slower velocity) mean anything?
Other than what you have stated, not really.
Skeet_man said:
Specifically when comparing bullets. One bullet .451" in diameter, 230 grains in weight, traveling at 880 feet per second. Second bullet .356" in diameter, 124 grains in weight, traveling 1200fps. Both bullets have 396 ft/lb of kinetic energy. However, in a somewhat ad-hoc comparison against targets, the larger slower bullet is ostensibly being shown to impart more force on the target, causing it to tip over, whereas the faster lighter bullet fails to do so.
Just for reference, a ft/lb is not a unit of energy by a ft*lb is. To answer your question, the faster bullet may just go through the target before it can transfer all of its energy to the target.
 
Skeet_man said:
However, in a somewhat ad-hoc comparison against targets, the larger slower bullet is ostensibly being shown to impart more force on the target, causing it to tip over, whereas the faster lighter bullet fails to do so.
The heavier slower bullet has more momentum, if kinetic energies are the same.

Assuming the bullet stays in the target:
- Momentum is relevant to moving/tilting the target.
- Energy is relevant to the damage/deformation of target/bullet.
 
Last edited:
@Skeet_man do you know how to calculate the kinetic energy and the momentum of a bullet? I

t seems to me that if you were looking at the equations, that you could answer your own question.
 

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