Kinetic energy, size of object, and force applied

• Skeet_man
In summary, it appears that the heavier bullet has more momentum, and therefore may be more effective when it comes to moving or tipping the target.
Skeet_man
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.

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.

1. What is kinetic energy?

Kinetic energy is the energy possessed by an object due to its motion. It is dependent on the mass and velocity of the object and can be calculated using the formula KE = 1/2 * m * v^2.

2. How does the size of an object affect its kinetic energy?

The size of an object does not directly affect its kinetic energy. However, the mass of the object, which is related to its size, does have an impact on the kinetic energy. A heavier object with the same velocity as a lighter object will have more kinetic energy.

3. What is the relationship between force applied and kinetic energy?

The relationship between force applied and kinetic energy is directly proportional. This means that as the force applied to an object increases, its kinetic energy also increases. This can be seen in the formula KE = 1/2 * m * v^2, where the mass remains constant but the velocity, and therefore the kinetic energy, increases with an increase in force.

4. Can the kinetic energy of an object be negative?

No, kinetic energy cannot be negative. It is a measure of the energy an object possesses due to its motion, and therefore it cannot have a negative value. However, if the velocity of an object is negative, the kinetic energy will be negative as well, indicating that the object is moving in the opposite direction.

5. How does kinetic energy change as an object's velocity changes?

The kinetic energy of an object changes proportionally to the square of its velocity. This means that as the velocity of an object increases, its kinetic energy increases exponentially. For example, if the velocity of an object is doubled, its kinetic energy will increase by a factor of four.

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