1. The problem statement, all variables and given/known data A car rubber has the volume 50 liters when it is bloated in a pressur 1.8 atm and in a temperature 293 K. After some hours of journey as an effect of friction the pressure will become 2atm. Find the change of internal energy of the air inside the rubber (U) 2. Relevant equations U=3/2nRT 3. The attempt at a solution I thought to sue the formula U=3/2nRT, but I don't know the n.