Small water droplets of radius 0.01 mm are formed in the upper atmosphere and falling with a terminal velocity of 10 cm / s . Due to condensation, if 8 such droplets are coalesced and formed a larger

Question

Small water droplets of radius 0.01 mm are formed in the upper atmosphere and falling with a terminal velocity of 10 cm / s . Due to condensation, if 8 such droplets are coalesced and formed a larger drop, the new terminal velocity will be _____ cm / s .

TestHub · Accepted Answer

m = mass of small drop M = mass of bigger drop ​ V t ​ = 9 2 ​ η R 2 ( ρ − σ ) g ​ 8 ∝ m = M 8 r 3 = R 3 ⇒ R = 2 R ​ as V t ​ × R 2 ∵ Radius double so V t ​ becomes 4 time ∴ 4 × 10 = 40 cm / s

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