Due to surface tension, the excess pressure inside a smaller drop is 9 units. If 27 smaller drops combine then excess pressure inside the bigger drop is

Step-by-step solution

Excess pressure inside a liquid drop of radius r is given by P = 2T r . For the smaller drop, P₁ = 2T r = 9 units. When 27 smaller drops combine to form a bigger drop of radius R , the total volume remains conserved. 4 3 R^3 = 27 4 3 r^3 R^3 = 27r^3 R = 3r The excess pressure inside the bigger drop is P₂ = 2T R . Substituting R = 3r , we get: P₂ = 2T 3r = 1 3 ( 2T r ) P₂ = 1 3 9 = 3 units. Answer: 3 units