Newton's Third Law - Weak Form Application

[DaTario]

Hi all,

I would like to know in which circunstances the third law applies just in the weak form.

Thank you

DaTario

 

[Shooting Star]

Mostly involving electromagnetic forces.

 

[DaTario]

Could you give an example. Doesn't the Lorentz force obey Newton's third law ?

 

[Shooting Star]

Consider two identical charges moving along the x and y axes with same speed away from the origin. The electrical forces between them is repulsive, but now just find out how the magnetic forces between them behave. You don't have to calculate -- just roughly think of the charges as currents and find the direction of the associated magnetic fields like we do for currents.

The total force of one on the other is equal to the force of the other on the former, but they are not opposite.

Ultimately, momentum will be conserved, because the fields themselves carry momentum.

 

[DaTario]

Thank you a lot.

Best wishes

DaTario

 

[alvaros]

Consider two identical charges moving along the x and y axes with same speed away from the origin. The electrical forces between them is repulsive, but now just find out how the magnetic forces between them behave. You don't have to calculate -- just roughly think of the charges as currents and find the direction of the associated magnetic fields like we do for currents.

The total force of one on the other is equal to the force of the other on the former, but they are not opposite.

Ultimately, momentum will be conserved, because the fields themselves carry momentum.

Any link where this example is further explained ?
Thanks.

 

[Shooting Star]

Here's an old discussion from the forum: https://www.physicsforums.com/showthread.php?t=94627

This looks interesting: http://sg.answers.yahoo.com/question/index?qid=20071007235358AAyEzOg

I'd suggest consulting some books on electrdynamics. Griffiths is good for the first time.