Can anyone explain following scenarios in Force-Reaction

In summary, when a larger mass object collides with a smaller mass object in a vacuum, both with zero net force and indestructible, they will bounce off of each other with equal force. However, if both objects are destructible, the higher mass object will likely go through the smaller mass object due to the equal distribution of force causing the objects to deform and move sideways. The total momentum of the system will remain constant in both cases, and it is important to consider momentum rather than just force when discussing collisions.
  • #36
Velocity2D said:
I don't really understand, since momentum is less each moment because if dissipating energy.
See post #32 and #34. You have to do your homework.
 
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  • #37
Velocity2D said:
How can swinging balls conserve momentum? The balls will have less momentum every moment, since energy dissipates? If the momentum was the same in the balls, the balls would never stop?
Here you go again. You can't make up your own rules. You need to believe that, in these classical matters, in particular. The system works. Use the (complete) system and don't try to invent your own system which you seem to have based on some but not all of the basics. As jbriggs says "You have to do your homework" and stop arguing that the system doesn't agree with you. It's the other way round.
 
  • #38
Well, as far as I understand this classical mechanics, the balls itself do lose their momentum but it stays the same in the "system", but when looking the single ball it does lose momentum. Momentum = v*m, and the velocity of the balls will drop over time because nothing can move forever, so it loses momentum.
 
  • #39
Velocity2D said:
Well, as far as I understand this classical mechanics, the balls itself do lose their momentum but it stays the same in the "system",
The "system" has boundaries where you define them to be. If you draw the boundaries so that the balls are in the system and the air and the frame and the strings and the Earth's gravity are outside the system then you do not have a "closed system" that is subject to zero net external force. Momentum is not guaranteed to be conserved if you do not have a closed system subject to zero net external force.
 
  • #40
jbriggs444 said:
The "system" has boundaries where you define them to be. If you draw the boundaries so that the balls are in the system and the air and the frame and the strings and the Earth's gravity are outside the system then you do not have a "closed system" that is subject to zero net external force. Momentum is not guaranteed to be conserved if you do not have a closed system subject to zero net external force.
I have trouble understanding, why talk about "systems"? Its not possible to include everything, because the system is bound to have boundaries and it loses momentum unless the whole universe is the "system", in which case momentum is constant like energy.
 
  • #41
Velocity2D said:
I have trouble understanding, why talk about "systems"? Its not possible to include everything, because the system is bound to have boundaries and it loses momentum unless the whole universe is the "system", in which case momentum is constant like energy.
Please do your homework.
 
  • #42
Those "Newtons balls" is just theoretical model to illustrate certain equations etc. But in reality there are no "closed circuits", everything affects evertything. Whenever we define any systems, there appears to be leakage of momentum, energy etc.

In case of Newtons balls-device, the balls lose their momentum to surrounding environment in forms of heat dissipation from friction between balls and air molecules, elastic damage to the balls etc.
 
  • #43
Velocity2D said:
In case of Newtons balls-device, the balls lose their momentum to surrounding environment in forms of heat dissipation from friction between balls and air molecules, elastic damage to the balls etc.
Kinetic energy is dissipated as heat, but not momentum. If momentum is transferred to the air, it stays momentum.
 
  • #44
I just don't understand, why heat isn't kinetic energy? Heat is movement of particles. If collision causes molecules to vibrate, isn't the kinetic energy conserved?
 
  • #45
Velocity2D said:
I just don't understand, why heat isn't kinetic energy? Heat is movement of particles.
That's why you can convert macroscopic KE (bulk movement) into microscopic KE (heat), or some other energy form. But there is only one form of linear momentum, which is also conserved, yet cannot be converted into something non movement related.
 
  • #46
A.T. said:
That's why you can convert macroscopic KE (bulk movement) into microscopic KE (heat), or some other energy form. But there is only one form of linear momentum, which is also conserved, yet cannot be converted into something non movement related.
But if momentum is conserved because the total mass and movement amounts to the momentum before and after, why isn't kinetic energy of moving particles in form of heat account for total kinetic energy the same way?
 
  • #47
Velocity2D said:
But if momentum is conserved because the total mass and movement amounts to the momentum before and after, why isn't kinetic energy of moving particles in form of heat account for total kinetic energy the same way?
Can you define momentum for us?
 
  • #48
jbriggs444 said:
Can you define momentum for us?
Momentum = mv

I understand that kinetic energy is scalar instead of linear, but shouldn't it still amount the same if billions of molecules/atoms are vibrating at very high speed?
 
  • #49
There is an essential and very practical difference between the KE of coherent motion and the KE of thermal motion. If any of the initial mechanical KE of the system gets transferred to thermal energy (possibly KE but not necessarily all KE), you can't get it back without the use of a heat engine. It is usual to treat mechanical situations like collisions by just sticking with the mechanical energy and the momentum and then regarding any deficit in KE as 'loss'.
The effect of drag in the air is most conveniently dealt with by introducing a drag force into the equations.
How would you justify a different approach? You seem to be suggesting that your idea of adding complexity is absolutely necessary? It would not be practical in most situations.
 
  • #50
I was trying to think, that there must be total amount of "kinetic energy" in form of general vibrations of particles that remains conserved, just like momentum. But I have no way to calculate and check if that is true so I am stuck with this hypothesis.

I have this problem also, that whenever I don't quiet understand something I feel I am stupid. This issue is perfect example of this, it is stated everywhere that kinetic energy isn't conserved but I fail to see the fundamental difference in how it is just not spread over large quantitis like momentum.
 
  • #51
Velocity2D said:
I understand that kinetic energy is scalar instead of linear, but shouldn't it still amount the same if billions of molecules/atoms are vibrating at very high speed?
It's not the same, because equal but opposite momenta cancel to zero, while kinetic energies from such motion don't.
 
  • #52
Velocity2D said:
there must be total amount of "kinetic energy" in form of general vibrations of particles that remains conserved..
No, because it can be converted into some form of potential energy.
 
  • #53
A.T. said:
No, because it can be converted into some form of potential energy.
But in the end, everything in this universe is movement of particles. Particles are never still, so all energy that there is, should be ultimately tied to the vibrations of particles/waves.
 
  • #54
Velocity2D said:
all energy that there is, should be ultimately tied to the vibrations of particles/waves.
No, because potential energy is not tied to movement.
 
  • #55
A.T. said:
No, because potential energy is not tied to movement.
But let's go deeper, what is potential energy? Since the very nature of wave-particles is the vibration (nothing is never at rest and there are particles transmitting the "potential energy"), the energy of the whole universe must therefore be kinetic by nature. I think classical mechanics isn't adequate enough to define world, and saying that kinetic energy isn't conserved is flawed view.

Also, forces are made of carrier particles, so when something is "at rest" they are actually communicating with other particles through thise force carriers. https://en.wikipedia.org/wiki/Force_carrier
 
  • #56
Velocity2D said:
saying that kinetic energy isn't conserved is flawed view.
If you redefine "kinetic energy" to mean total energy, then it will be conserved classically.
 
  • #57
Big mass hits small mass ... F = m1 x A1 = m2 x A2 good grief you guys !
 
<h2>1. What is force-reaction and how does it work?</h2><p>Force-reaction is a principle in physics that states for every action, there is an equal and opposite reaction. This means that when an object exerts a force on another object, the second object will exert an equal force back on the first object in the opposite direction. This is based on Newton's Third Law of Motion.</p><h2>2. Can you give an example of force-reaction in everyday life?</h2><p>One example of force-reaction in everyday life is when you push a door open. When you push on the door, you are exerting a force on it. The door then exerts an equal and opposite force back on you, allowing the door to open.</p><h2>3. How does force-reaction apply to objects in motion?</h2><p>Force-reaction applies to objects in motion by affecting their acceleration. When a force is applied to an object, it will accelerate in the direction of the force. The equal and opposite reaction force will also affect the object's motion, causing it to accelerate in the opposite direction.</p><h2>4. Can force-reaction be seen in the natural world?</h2><p>Yes, force-reaction can be seen in the natural world. For example, when a bird flaps its wings, it exerts a force downwards, which creates an equal and opposite reaction force that lifts the bird into the air. Another example is when a fish swims, it pushes against the water with its fins, and the water pushes back with an equal and opposite force, propelling the fish forward.</p><h2>5. How is force-reaction used in engineering and design?</h2><p>Force-reaction is an important principle in engineering and design. It is used to calculate and predict the forces acting on structures and objects, which is crucial in ensuring the safety and stability of buildings, bridges, and other structures. Understanding force-reaction also allows engineers to design machines and devices that can efficiently and effectively use forces to perform specific tasks.</p>

1. What is force-reaction and how does it work?

Force-reaction is a principle in physics that states for every action, there is an equal and opposite reaction. This means that when an object exerts a force on another object, the second object will exert an equal force back on the first object in the opposite direction. This is based on Newton's Third Law of Motion.

2. Can you give an example of force-reaction in everyday life?

One example of force-reaction in everyday life is when you push a door open. When you push on the door, you are exerting a force on it. The door then exerts an equal and opposite force back on you, allowing the door to open.

3. How does force-reaction apply to objects in motion?

Force-reaction applies to objects in motion by affecting their acceleration. When a force is applied to an object, it will accelerate in the direction of the force. The equal and opposite reaction force will also affect the object's motion, causing it to accelerate in the opposite direction.

4. Can force-reaction be seen in the natural world?

Yes, force-reaction can be seen in the natural world. For example, when a bird flaps its wings, it exerts a force downwards, which creates an equal and opposite reaction force that lifts the bird into the air. Another example is when a fish swims, it pushes against the water with its fins, and the water pushes back with an equal and opposite force, propelling the fish forward.

5. How is force-reaction used in engineering and design?

Force-reaction is an important principle in engineering and design. It is used to calculate and predict the forces acting on structures and objects, which is crucial in ensuring the safety and stability of buildings, bridges, and other structures. Understanding force-reaction also allows engineers to design machines and devices that can efficiently and effectively use forces to perform specific tasks.

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