Volume 6, 2022
|Number of page(s)||5|
|Published online||01 June 2022|
Suction-ejection of a ping-pong ball in a falling water-filled cup
Magistère de physique d’Orsay, Université Paris-Saclay,
Accepted: 20 December 2021
Dropping a water-filled cup with a ping-pong ball inside to the ground expels the ball much higher than its initial height. During free fall, the absence of gravity in the reference frame of the cup makes capillary forces dominant, causing the ball to be sucked into water. At impact, the high velocity ejection is due to the strong Archimedes’ force caused by vertical acceleration. In this paper, we study the dynamics of the capillary sinking of the ball during free fall and the ejection speed at impact, using tracking and high-speed imaging. In particular, we show that at short-time, the sinking is governed by capillary and added mass forces.
Key words: Capillary Suction / Surface Tension / Free Fall / Buoyancy
© A. Barlet and N. Malhomme, published by EDP Sciences, 2022
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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