View Full Version : change in relativistic momentum
kurious
Aug21-04, 11:20 AM
Is it alright to say that force = rate of change of relativistic momentum
F = [ m0 v2 / (1 - v2^2/c^2)^1/2 - m0 v1/(1 - v1^2/c^2)^1/2 )] / (t2 - t1)
and can this relation be used to get sensible results for particles?
Is it alright to say that force = rate of change of relativistic momentum
F = [ m0 v2 / (1 - v2^2/c^2)^1/2 - m0 v1/(1 - v1^2/c^2)^1/2 )] / (t2 - t1)
and can this relation be used to get sensible results for particles?
Thats close to ordinary force f. To be precise ordinary force f involves the limit of that as t2-t1 becomes infinitesimal dt in a calculus limit. Also, you shouldn't subscript the mass with a zero as it is invariant.
DW is right, your notation is wrond. You must let t2-t1 approach 0, it must be alimit.
Here is the wau you want to write it:
F = \frac {d(\frac{mv}{\sqrt{1-v^2 / c^2}})}{dt}
Yes, but in general, you gain nothing in writing the differential equation in terms of velocity. Just leave it in momentum; equations are far simpler.
pmb_phy
Aug21-04, 02:06 PM
Is it alright to say that force = rate of change of relativistic momentum..Yes. Force is defined as
\bold F = \frac{d\bold p}{dt}
F = [ m0 v2 / (1 - v2^2/c^2)^1/2 - m0 v1/(1 - v1^2/c^2)^1/2 )] / (t2 - t1)
and can this relation be used to get sensible results for particles?That is the average force. The instantaneous force is F = dp/dt.
Pete
Yes. Force is defined as
\bold F = \frac{d\bold p}{dt}
That is the average force. The instantaneous force is F = dp/dt.
Pete
Just to be clear to you, in light of the notation having been used here for a while, it is an expression for ordinary force f, not the four-vector force F.
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