Physics, asked by mudit2005dps, 5 months ago

an momentum be hidden to human eyes like how kinetic energy can be hidden as heat?

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Answered by Anonymous

Yes and no. In a regular mechanical system with macroscopic parts, momentum can not be "hidden" to human eyes. But in other systems, momentum can be hidden. For instance, in an electromagnetic system, momentum can be transferred to the electromagnetic field, which is invisible to human eyes at most frequencies. Therefore, momentum can be "hidden" in the electromagnetic field. Let us explore this topic more in depth.hockeyPublic Domain Image, source: William D. Moss, U.S. Department of DefenseEvery isolated system obeys the law of conservation of energy which states that if no energy is externally extracted or inserted into the system, its total energy will remain constant in time. For example, consider two hockey pucks sliding towards each other on ice. If you sum the kinetic (motional) energy of both pucks before they collide, you will find that it equals the sum of both energies after they collide. We can in fact use the conservation of energy along with some other information to predict what will happen in a simple collision like this.

Yes and no. In a regular mechanical system with macroscopic parts, momentum can not be "hidden" to human eyes. But in other systems, momentum can be hidden. For instance, in an electromagnetic system, momentum can be transferred to the electromagnetic field, which is invisible to human eyes at most frequencies. Therefore, momentum can be "hidden" in the electromagnetic field. Let us explore this topic more in depth.hockeyPublic Domain Image, source: William D. Moss, U.S. Department of DefenseEvery isolated system obeys the law of conservation of energy which states that if no energy is externally extracted or inserted into the system, its total energy will remain constant in time. For example, consider two hockey pucks sliding towards each other on ice. If you sum the kinetic (motional) energy of both pucks before they collide, you will find that it equals the sum of both energies after they collide. We can in fact use the conservation of energy along with some other information to predict what will happen in a simple collision like this.But now suppose we fire the two pucks directly at each other at the same speed and cover their sides with perfect glue. What happens? Of course, when the pucks make contact, they stick together and both end up with zero speed, and therefore zero kinetic energy. This means that the total kinetic energy of the two-puck system at the beginning was some big number, but the total kinetic energy at the end was zero (at least according to human eyes). Has the glue broken the law of conservation of energy? No. If you did a careful analysis of this event, and measured everything you could think of, you would find that the heat (thermal energy) in the two pucks increases after the collision by the exact same amount as the kinetic energy that seemed to disappear (neglecting the friction of the ice). The macroscopic kinetic energy has therefore been converted into heat. The law of conservation of energy still holds as long as we add heat as one of the things that contributes to the total energy. Such a collision is called an inelastic collision.

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