Simple and Stupid Doubt

If you include non-inertial frames then u must include the pseudo force.. If after considering the pseudo force the net force on the system becomes zero, then u can conserve momentym i think

But Irodov says something else
Acc to Irodov,
"We emphasize once again that the momentum conservation
law holds only in inertial frames. This statement, however,
does not rule out the momentum of a system remaining
constant in non-inertial reference frames as well. This
happens when in Eq. (4.4), which is also valid in non-inertial
reference.lframes, the external force F (including inertial
forces) is equal to zero. Clearly this situation occurs only
under specral conditions. Such special cases are fairly rare."

dp/dt = F ............(eqn 4.4)
Then , what r the special cases ????

the important thing in the momentum conservation principle is that whatever be the momentum with respect to any frame ,that value of momentum does not change for an observer in that frame, if the external forces add up to zero !

the first thing is when can we conserve momentum....only when all impulses are taken into the system so that they cancel out...

so when u take non inertial frame..then as asish said there will be pseudo force which will depend on accelration of frame and masses...so for any general case that pseudo force's impulse (if exists) wont always sum up to be zero in the system..though it may happen for special cases when impulses become equal and hence cancel out...thus enabling us to conserve the momentum...