JEE Main202228 Jun 2022Morning ShiftPhysicsMechanical Properties of FluidsActual
A water drop of diameter 2 cm is broken into 64 equal droplets. The surface tension of water is 0 . 075 N m - 1 . In this process the gain in surface energy will be
Options
- A2 . 8 × 10 - 4   J
- B1 . 5 × 10 - 3   J
- C1 . 9 × 10 - 4   J
- D9 . 4 × 10 - 5   J
Correct answer
A. 2 . 8 × 10 - 4   J
Step-by-step solution
By conserving the total volume 4 3 π R 3 = 64 × 4 3 π r 3 ⇒ R = 4 r Change in surface energy is Δ U = T × Δ A , = T 64 × 4 π r 2 - 4 π R 2 = 4 π T R 2 64 × 1 16 - 1 = 12 × 3 . 14 × 0 . 075 × 10 - 4 ≈ 2 . 8 × 10 - 4   J