See post #32 and #34. You have to do your homework.Velocity2D said:I don't really understand, since momentum is less each moment because if dissipating energy.
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.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?
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.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",
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.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.
Please do your homework.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.
Kinetic energy is dissipated as heat, but not momentum. If momentum is transferred to the air, it stays momentum.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.
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.Velocity2D said:I just don't understand, why heat isn't kinetic energy? Heat is movement of particles.
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?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.
Can you define momentum for us?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?
Momentum = mvjbriggs444 said:Can you define momentum for us?
It's not the same, because equal but opposite momenta cancel to zero, while kinetic energies from such motion don't.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?
No, because it can be converted into some form of potential energy.Velocity2D said:there must be total amount of "kinetic energy" in form of general vibrations of particles that remains conserved..
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.A.T. said:No, because it can be converted into some form of potential energy.
No, because potential energy is not tied to movement.Velocity2D said:all energy that there is, should be ultimately tied to the vibrations of particles/waves.
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.A.T. said:No, because potential energy is not tied to movement.
If you redefine "kinetic energy" to mean total energy, then it will be conserved classically.Velocity2D said:saying that kinetic energy isn't conserved is flawed view.