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I was wondering why in special relativity that the force when the velocity is parallel to the force the force = dP/dt= [tex]\gamma[/tex]^3 ma, whereas when the velocity is perpendicular to the force the force = dP/dt= [tex]\gamma[/tex] ma. Why is this? Is it because when the velocity is parallel to the force both the velocity of the gamma and v in the momentum, [tex]\gamma[/tex]mv, changes, thus the product rule applies, whereas when the velocity is perpendicular only the velocity in the momentum changes not the velocity in the gamma, thus the product rule does not apply?

Thanks for the help in explain this.

Stephen

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# Homework Help: Special Relativity and Force

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