- #1

simphys

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- Homework Statement
- (I) Two railroad cars, each of mass 56,000 kg, are traveling

##95km/h##toward each other. They collide head-on and come

to rest. How much thermal energy is produced in this collision?

- Relevant Equations
- law of conserfvation of energy

this is an easy problem but would it be possible to consider car-car system. What I did on paper was carsystem and because they have the same properties(mass en speed) multiply by ##2##

solution for car-car-earth system I assume is the following if it is possible?

solution for car-car:

law or conservation of energy says:

##E_1 = E_2 + W_{th}##

##\frac12m_{c1}v_{1,c1}^2 + \frac12m_{c2}v_{2,c2}^2 = 0 + W_{th}##

massses same, velocity same so :

##W_{th} = mv^2 = 3.9E7J##

Thanks in advance

Edit: ;earth not included

solution for car-car-earth system I assume is the following if it is possible?

solution for car-car:

law or conservation of energy says:

##E_1 = E_2 + W_{th}##

##\frac12m_{c1}v_{1,c1}^2 + \frac12m_{c2}v_{2,c2}^2 = 0 + W_{th}##

massses same, velocity same so :

##W_{th} = mv^2 = 3.9E7J##

**edit: What I actually want reassurance of is.. this is all dependent on the system and if we take car-car system we consider all the energies of the involved objects by examining all of 'em seperately.**I am asking stuff like this because it's kinda important but not really mentioned only implicitly in the bookThanks in advance

Edit: ;earth not included

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