 Welcome back to Kids Fun Science. My name is Ken. Today's experiment is surface tension with a ping-pong ball. As always, adult supervision is required. What you need for this experiment is a ping-pong ball, water, a cup or bowl, and dish soap. So it's quiz time. Can you put a ping-pong ball in the center of a cup of water and not have it move to the side? Let's see if we can. This experiment you fill up a cup of water, put the ping-pong ball in the center, and you'll see it's drawn to the side of the cup on this three inch cup. Now I try to five inch cup, put the ping-pong ball in the middle, same results. And then one more time with an eight inch bowl, and put it in the middle. It takes a little bit longer, but eventually it goes to the side of the bowl. This time I'm going to take a little bit of dish soap to the three inch cup, place it on tip of my finger, and put it on the surface tension. When the soap is added, the surface tension is reduced, and the path to the minimum surface area is less steep. As such, the ball will drift much more slowly to the end and appear to almost be stable at some points. I ended up doing this almost 30 or 40 seconds, and it just started to go to the edge, where the first experiment with the three inch cup, it took about five seconds to get to the end. So pretty impressive that the soap breaking down that surface tension. Placing the ping-pong ball at the surface of the water creates a curvature in the water surface all the way around the ball. The surface tension will act as a minimum total surface area, unless you place that ball exactly in the middle of the cup, which is nearly impossible. There is an asymmetry of the surface curvature that will draw the ball towards the side, nearest to the ball, through us minimizing the total surface area. I hope you enjoyed this video. Remember to click thumbs up below and to subscribe. Thanks for watching.