Question

A garden hose of diameter 2 cm is used to fill a 20 liter bucket. If it takes 1 minute to fill the bucket, what is the speed at which water enters the hose?

(a) 106.1 cm/s

(b) 106 cm/s

(c) 106.5 cm/s

(d) 106.8 cm/s

The question was asked in an online interview.

The above asked question is from Fluids in Motion topic in portion Fluid Flow and Mixing of Bioprocess Engineering

Answer 1

Correct answer is (a) 106.1 cm/s

To explain: The cross-sectional area of the hose will be given by:

A1 = π r^2 = π (2 cm/2)^2 = π cm^2

To find the velocity, v1, we use

Flow rate = A1 v1 = 20.0 L/min = \(\frac{20.0 × 10^3 cm^3}{60.0 s}\)

v1 = \(\frac{20.0 × \frac{10^3 cm^3}{60.0s}}{\pi cm^2}\)

= 106.1 cm/s