Can internal manipulation affect the kinetic energy of a moving object?

In summary: Originally posted by NateTG I believe some electromagnetic interactions do violate Newton's third law. (But in my coffee-deprived state I can't think of any specifics.) However, I don't agree that this implies a violation of momentum conservation. It would imply it, if Newton's third law were required for momentum conservation to hold, but I don't think that's true. Conservation of momentum is more fundamental than Newton's third law.
  • #1
pallidin
2,209
2
Is there a way that the kinetic energy of a moving object can be locally and internally absorbed or otherwise altered without outside influence?
For example, let's say that I have a container that has been fired out of a cannon at 100 mph. Now, this container has an abundant internal energy source available for anything expect outside thrust, as outside thrust is not permitted in any way(for this experiment)
Since the internal mass of the container is a direct function of the containers kinetic energy, can the internal mass be manipulated in-flight such to where the manipulation changes the strength or vectors of the containers kinetic energy?
Again, for example, if there were 2 lead balls of x-amount of weight affixed on the inside side walls of the container, and the internal energy source cause them to be violently pulled together towards the center of the container, does this action in any way affect the total kinetic energy of the containers motion?
Thank you greatly for your time and expertise.
 
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  • #2
The linear mometum cannot be changed without outside interaction, but you can increase the kinetic energy by having parts of the projectile move relative to each other. If you want the system to be closed, then this would only affect the projectile's rotational kinetic energy.
 
  • #3
NateTG:

I understand what you have said, and I appreciate your comments. So is their no way at all to decay single vector kinetic energy in a closed system?
Thank you for your continued time.
 
  • #4
"Closed" meaning free-flight with no additional external influence. Static systems(i.e. shock absorbers with earth-ground reactionary forces)are understood not to be applicable in this scenario.
 
  • #5
Kinetic energy has no direction. I think you mean momentum.

Anyways, a closed system cannot change its own momentum if Newton's 3rd law is obeyed. Electromagnetism doesn't follow Newton's laws, so it is possible to alter your trajectory in flight.
 
  • #6
Originally posted by Stingray
Kinetic energy has no direction. I think you mean momentum.

Anyways, a closed system cannot change its own momentum if Newton's 3rd law is obeyed. Electromagnetism doesn't follow Newton's laws, so it is possible to alter your trajectory in flight.

This is news to me, could you please elaborate.
 
  • #7
Originally posted by Integral
This is news to me, could you please elaborate.
I believe some electromagnetic interactions do violate Newton's third law. (But in my coffee-deprived state I can't think of any specifics.) However, I don't agree that this implies a violation of momentum conservation. It would imply it, if Newton's third law were required for momentum conservation to hold, but I don't think that's true. Conservation of momentum is more fundamental than Newton's third law.

Hopefully there's an expert in the wings who can confirm this.
 
  • #8
Look at the Biot-Savart law for example. Its very simple to set up situations which violate the strong form of the 3rd law (non-parallel wires).

In more dynamic situations, you can violate the weak form as well. This is mentioned in the Feynman lectures for example.

Momentum conservation still works as long as you take account of the momentum contained in the fields. If you only look at the material objects, momentum can be changed.
 

1. What is Absorbing Kinetic Energy?

Absorbing kinetic energy refers to the process of taking in or receiving the energy of motion from an object or system. This can happen through various mechanisms such as friction, deformation, or conversion to other forms of energy.

2. Why is it important to absorb kinetic energy?

Absorbing kinetic energy is important because it helps to reduce the amount of energy that is transferred to other objects or systems. This can prevent damage, injuries, or other negative consequences that may result from the transfer of excessive kinetic energy.

3. How does the absorption of kinetic energy occur?

The absorption of kinetic energy can occur through different processes depending on the situation. For example, in a collision between two objects, kinetic energy can be absorbed through deformation of the objects' surfaces. In a braking system, kinetic energy can be absorbed through friction between the brake pads and the rotating wheels.

4. Can materials be designed to better absorb kinetic energy?

Yes, materials can be designed or engineered to have specific properties that allow them to better absorb kinetic energy. For example, materials with high ductility and low stiffness are better at absorbing kinetic energy through deformation, while materials with high friction coefficients are better at absorbing kinetic energy through friction.

5. How is the absorption of kinetic energy related to safety?

The absorption of kinetic energy is closely related to safety in many applications. For instance, in the automotive industry, the design of car bumpers and crumple zones is crucial for absorbing kinetic energy in the event of a collision to protect passengers. In sports, protective gear such as helmets and padding are designed to absorb kinetic energy and reduce the risk of injury.

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