Question

. What should be the diameter of a soap bubble, in order that the excess pressure inside it is 51.2 N/m2 ? (S.T. of soap solution = 3.2 × 10–2 N/m)

Answer 1

Given :

excess pressure =P = 51.2 N/m2  

T = 3.2 × 10⁻² N/m  

P = 4T /r  

P = 4T/ r  

∴ r = 4T P  

r = 4 x3.2 10⁻² /51.2  

= 2.5 × 10⁻³  

d = 2r

∴ d = 5 × 10⁻³ m

Answer 2

Given :

excess pressure =P = 51.2 N/m2  

T = 3.2 × 10⁻² N/m  

P = 4T /r  

P = 4T/ r  

∴ r = 4T P  

r = 4 x3.2 10⁻² /51.2  

= 2.5 × 10⁻³  

d = 2r

∴ d = 5 × 10⁻³ m