Question

In a capillary tube experiment, a vertical, 30 cm long capillary tube is dipped in water. The water rises up to a height of 10 cm due to capillary action. If this experiment is conducted in a freely falling elevator, the length of the water column becomes ___________

(a) 10 cm

(b) 20 cm

(c) 30 cm

(d) Zero

I have been asked this question in a national level competition.

I would like to ask this question from Thrust of a Liquid topic in portion Mechanical Properties of Solids of Engineering Physics I

Answer 1

Right option is (c) 30 cm

The explanation: In the freely falling elevator, g = 0.

Water will rise (h=2σcosθ/rρg) to fill the entire 30 cm length of the tube.