Question

The soap bubble formed at the end of the tube is blown very slowly. Draw the graph between excess of pressure inside the bubble with time.

Answer 1

As excess of pressure inside the soap bubble of radius r is `p=(4S)/(r ) , i.e . P prop 1/r`
i.e. as r increases with time , p decreases.
So, the variation of p with time(t) will be a parabolic curve AB as shown in fig.