A video of a leaf with ink on it zooming through the puddle of water has amused the internet. Shared by the official handle of the wonder of science on Twitter, the 13-second clip shows a green leaf propelled with force like a boat in the water. The clip is captioned that the pen ink on the leaf changes the surface tension of the water behind it, thus propelling the leaf forward with trails behind in a unique phenomenon known as the Marangoni effect.
With over 171.7k views and 12k likes, the clip sparked a huge reaction in the comments as users shared their own little experiments with the “Marangoni effect”. In another video shared by Wonder of Science, it tutored on how to make one’s own paper boat at home and power it with this phenomenon.
A science research explains that usually, at the border between the boat and the water’s surface, the water actively “pulls” the boat to itself. Directly proportional to surface tension, this force tends to pull the boat in all directions equally, and therefore the boat remains stationary. However, if one adds ink or soap, these products cotain surfactants, which reduce the surface tension of the water. And therefore, this weakens the water’s “grip” on the boat significantly and it seems that the ink pushes the boat forward creating the impressions.
Ink on a leaf zooming around a puddle.— Wonder of Science (@wonderofscience) May 14, 2020
The ink has a lower surface tension than water, creating a surface tension gradient that pulls the leaf forward, a phenomenon known as the Marangoni effect. pic.twitter.com/tsWjpvpLGH
Soap molecules separate water molecules. As distance between them increases, surface tension decreases in that region.— Call me Bond, Hydrogen Bond. (@Razor_53) May 15, 2020
Wow!!!— Allen Porto (@allenporto) May 14, 2020
I remember doing this experiment when I was little.— Kappa Nitori (@Nitori__K) May 15, 2020
Cool! Maybe a way to generate power/spin a turbine @ a larger scale.— Meriel Gibson (@mmvgibson) May 15, 2020
This is really cool!— Dr. Shadow (@megadave5000) May 15, 2020
Makes me think of the 3 Body problem trilogy!— Emilio Garofalo Neto (@Emiliogarofalon) May 14, 2020
“You can do the same thing with a drop of dish detergent. Has to do with disrupting the surface tension of the water. I will say though that the ink seems to do a better job. Note that you likely won’t be able to do it more than once to the same puddle. For those curious. Fill a bowl with water, pour in a bunch of table pepper, and use a toothpick dipped in dish detergent. Same principle. Good bar trick” wrote a user on Reddit. “Quite beautiful,” wrote another. “Wouldn't that be considered as magic centuries ago,” wrote the third. The video about the effect was also shared on YouTube with a caption, "The differences of surface tension between soap and water can really make things go! This video shows some interesting demos illustrating the Marangoni Effect. Two liquids with different surface tensions will result in a surface tension gradient, resulting in a net force."