1. "w" grams of a specific fuel is burnt in a steel box of volume "V". the calorific value of fuel is given , suppose "c", now we have to calculate the force exerted on the steel walls of the box due to expansion of air inside the box due to burning of fuel. what will b the presure change? if the volume of the box could be changed .. to what volume will the inside air expand upto? Part 2: consider the figure; Supposing the box has an opening into a pipe of cross-section area, a1 , and pipe is attached to this opening with a massless piston(as shown in the figure). When the air in the box would expand, it pushes the piston to the other end. Now, supposing the pipe to be of infinite length, to what distance will the massless piston travel, till it comes to a stop? do not consider the loss of heat from any surface, assume the piston to be air-tight. 2. Relevant equations: no idea .. am pretty confused .. anyone mind tellin me?? 3. My trial: For the second part, the teacher gave the hint: the piston must develop some momentum due to which it will keep moving untill there is development of vaccum in the box and the vaccum force will cause the piston to stop. Now what is vaccum force??