Eight equal drops of water are falling through air with a steady speed of 10 ~cm / s . If the drops coalesce, the new velocity is:

Step-by-step solution

Let r be the radius of small drops of water. R = radius of big drop formed as volume remain same. 8 . 4 3 r ^3- 4 3 R ^3 R =2 r Terminal velocity, aligned & v _ T = 2 9 ( - ) r ^2 ~g & v _ T r ^2 & v ₁ v ₂ = ( r R )^2 & 10 v ₂ = ( 1 2 )^2 ( v ₁=10 ~cm / s given ) & v ₂=40 ~cm / s aligned