Question

A liquid flows out drop by drop from a vessel through a vertical tube with an internal diameter of 2 mm, then the total number of drops that flows out during 10 grams of the liquid flow out ______. [Assume that the diameter of the neck of a drop at the moment it breaks away is equal to the internal diameter of tube and surface tension is 0.02 N/m].

Options

• 780

• 750

• 650

• 950

Answer 1

A liquid flows out drop by drop from a vessel through a vertical tube with an internal diameter of 2 mm, then the total number of drops that flows out during 10 grams of the liquid flow out 780.

Explanation:

If m is mass of single drop then as it drops

mg = 2 πrT

If number of drops in M = 10 grams is N then, 

N = `"M"/"m"= "Mg"/"mg"= "Mg"/(2pi"rT")` ≈ 779.86 ≈ 780