Hi Harshita.Thanks for your question! There are lots of sums that are used to find out what is going on inside the airways of an asthmatic – an important one however is Hooke’s law! This is where the force applied to a spring, to stretch or compress it by some distance, is proportional to that distance. This equation is applied here because the airway is made of muscle cells that also stretch like a spring. We can therefore think of it as being made up of thousands of tiny springs that are connected together!