JEE Main20252 Apr 2025Evening ShiftPhysicsMechanical Properties of FluidsActual
Two water drops each of radius 'r' coalesce to from a bigger drop. If ' T ' is the surface tension, the surface energy released in this process is :
Options
- A4 r ^2 ~T [2-2^ 2 3 ]
- B4 r^2 ~T [2-2^ 1 3 ]
- C4 r^2 ~T [1+ 2 ]
- D4 r^2 T[ 2 -1]
Correct answer
A. 4 r ^2 ~T [2-2^ 2 3 ]
Step-by-step solution
aligned & 2 4 3 R ^3= 4 3 r ^3 r =2^ 1 / 3 R & U _ i =2 4 R ^2 ~T & U _ f =4 r ^2 ~T =4 R ^2 ~T 2^ 2 / 3 & Heat lost = u _ i - u _ f =4 R ^2 ~T [2-2^ 2 / 3 ] aligned