1. The problem statement, all variables and given/known data When a syringe with its end sealed is heated, the piston is pushed back such that the gas pressure in the syringe remains the same. Since the force exerted is dependent on 1) frequency of collision with the walls and 2) the force of the collisions. So comparing before and after heating, is the frequency higher and is the force hitting higher? also, is it possible to ask this question: more air is pumped into a filled incompressible tyre and it is put in a cooler. How has the pressure change? Or this: Air is drawn out of a filled incompressible tyre and it is also heated up. How has the pressure changed? 2. Relevant equations PV=PV but T is not constant here so I don't think this is applicable? 3. The attempt at a solution The answer key gave the frequency to be the same as before but doesn't the average kinetic energy of the air particles increase? So won't the frequency be subsequently higher as well. Also, if the frequency remains constant doesn't it also mean that the force of collision is the same as well? So going with the same explanation why would the air hit with less force? For the other 2 questions I posed, I don't think it is possible to answer them directly because they are contrasting (add air increase P cool reduce P, draw out air reduce P heat increase P). So just this empirical data will not tell us which phenomenon has a greater magnitude which doesn't allow me to say what will happen? But if eg a question says: a water bottle is filled partially with hot water and it expands slightly. Explain in terms of the kinetic model of matter this phenomenon. In this case, air is drawn out as water displaces some of it so pressure decreases, but since they already told us that the bottle expands, that means the pressure must have increased. Hence, the increase in temperature leads to the increase in pressure and this increase is more than the decrease in pressure by the removal of air? However, this example is also weird be because water pressure should be more than air pressure? I'm quite confused with this. Thanks for the help!