well it depends whether the car has passed paul or not ...whatever the case might be we are not interested in that as we have to only calculate the kinetic energy in which the sign makes no diffrence
the train is going in opposite direction of the car or accorgdng to paul the car is moving backwards...while calculating the relative speed you havnt taken the sign of velocties...if you rightfully consider the signs then it will be -100-100=-2009according to paul the car is moving backwards...
its kinetic energy is 0 in the first case and 16 in second...and the body will do work according to the kinetic energy in the frame of reference only .so in the first case no work will be done
are trying to say that if paul knows that in the second section the car takes 3x amount of fuel against 5/3 as calculated by him then he can logically conclude that he is a part of bigger system and is not looking at the whole thing
the fuel required for 0 to 100 in peters frame is same as the fuel required 100 to 200 in pauls frame...and if u are trying to sat that paul is making mistake by adding trains velocity then how how can conclude that he is making a mistake...becuase he can never know whether he is moving or the...