Simple Question ,

Consider two objects namely $A$ and $B$ where $B$ is stationary and $A$ is moving towards $B$ with velocity $v$.

When the two objects touch each other what does actually happen between them that $B$ moves.

  • Does the momentum get transferred.

  • Also is momentum a physically property that can be transferred.

(If you think somehow really somehow a non physical property like energy is transferred please answer question with regard to it).

  • If so How?

I mean what is the process of transfer of momentum.

If the momentum is transferred physically or in very simple words somehow flows .And if It can .Will there be a change in fundamental idea of the process of transfer of it.

For sake of simplicity lets take both objects rigid particles.

I really need Help .

Thank You .


1 Answer 1


"For sake of simplicity lets take both objects rigid particles."

Well, we can't both do this and answer your question. In such a model, we really just imagine that the particles experience an infinite force for an infinitesimally small amount of time (a dirac delta function). So in this model, momentum is mysteriously acquired instantly.

In reality, the two objects interact via the electromagnetic force, where force is gradually applied over time. We get the change in momentum by adding up the force at each point times the time it acted.

Hope this helped! I went no more in depth than I thought necessary but I think it should answer your question.

  • $\begingroup$ Sorry but what do you mean by infinite force.If particles are not rigid will force be finite.If so why? $\endgroup$ Jan 9, 2016 at 14:24
  • $\begingroup$ Keep in mind there are no such things are rigid particles. They are just a model we use to calculate things. The only thing that a particle being rigid does is keeps its geometry constant so we can see what angle it bounces off at (if the balls were squishy past the point where rigidity was a good approximation, then it would be a much more complicated problem). It is an infinite force because since we assume they collide at an instant, basically for near zero time, they need to have an "infinite" force to generate a finite change in momentum. $\endgroup$
    – SSD
    Jan 9, 2016 at 14:28
  • $\begingroup$ Just forget about the rigid particles applying to reality and think of them as a model we use to approximate reality. But in actual reality, there are electromagnetic fields that interact when you push objects too close to each other. In reality, these forces are extremely large (think near infinite), and the interaction time is extremely small (near zero). But in the rigid object approximation, we say the force is infinity and the time is zero and we get away with it. Follow? $\endgroup$
    – SSD
    Jan 9, 2016 at 14:32
  • $\begingroup$ I need to learn about electromagnetic interaction.I was trying to understand newtonian mechanics.Can you suggest some books that will make motion more clear to me $\endgroup$ Jan 9, 2016 at 14:41
  • $\begingroup$ What is your background in physics? How old are you? High school, college? How long have you been learning Newtonian mechanics, and what resources have you been using? It seems like you should probably get really good at Newtonian mechanics first before looking into electrodynamics. You don't need to know much though. Like charges repel, opposite charges attract. $\endgroup$
    – SSD
    Jan 9, 2016 at 15:12

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