Question

Eight equal drops of water are falling through air with a steady speed of \( 10 \, \text{cm/s} \). If the drops coalesce, the new velocity is:

• A. \( 10 \, \text{cm/s} \)
• B. \( 40 \, \text{cm/s} \)
• C. \( 16 \, \text{cm/s} \)
• D. \( 5 \, \text{cm/s} \)

Hint:

When drops merge, the radius of the combined drop increases as the cube root of the total volume. Since terminal velocity depends on the square of the radius, the new velocity scales quadratically with the radius increase.