Smaller Balloon Stronger Balloon - English

Smaller Balloon stronger Balloon – Air Pressure
This is a wonderful and counterintuitive experiment WHICH can BE DONE WITH ordinary materials which are readily available in your house. you need a rubber tube, few balloons, a thread, clamps, and a pair of scissors.
Seal one end of the rubber tube with clamp, Inflate a balloon and fix it to one end of the rubber tube with the help of a thread. Inflate another balloon to a smaller size and fix it to the other end of the tube. Make sure that there is no air leakage from the balloons.
Now that the setup is ready, guess what will happen when we open the clamp?

Most people think the air will flow from the big balloon towards the small one and eventually, both the balloons will be of the same size.

Surprisingly, it’s the opposite scenario, the air flows from the small balloon towards the bigger balloon expanding it even further
So why does this happen? As you know, air always flows from higher pressure towards lower pressure which means the smaller balloon has higher air pressure inside compared to the big one. This phenomenon can be explained by Laplace equation.
According to the Laplace equation, there exists a pressure difference in curved surfaces. As the radius decreases, the pressure difference increases i.e., the radius of the curvature (r) is inversely proportional to the pressure (P).
P ∝ 1/r
Since the radius of the small balloon is less than the radius of the big one, it has greater curvature and hence more pressure in it.
This explains why air flows from small balloon to big balloon
now let's try this with two small balloons at one end of rubber tube and a bigger balloon at the other end of the rubber tube. For this experiment, a “Y” shaped joint is made on the rubber tube to which the two small balloons are attached. Upon opening the clamp the air flows from smaller balloons towards the bigger balloon.
If you are more ambitious you can try this experiment with two different sized soap bubbles. Make a slant cut at one end of the straw and insert it in the other end. now bend both the ends of straw and make a U shaped assembly. Make a small hole and Insert the used refill at the center of the assembly. Make four petal-like cuts with the scissors on the open ends of the straws. Block one arm of the straw with clamp and dip the other end in soap solution. Blow air to make a small bubble. Now, close the other arm of the straw and blow air to make a bigger soap bubble. When we remove the clamp you observe a similar effect and the Air in the smaller bubble will flow towards the bigger bubble.
I hope you liked this experiment and learned something new today. For more hands-on science experiments and DIY science crafts, you can visit our YouTube channel which is “IISER Pune science activity center” and subscribe to the same. Have a Fun!

Team: Ashok Rupner, Chaitanya Mungi, Shraddha Bhurkunde, Neha Apte, Atul Gavade, Sandeep Jadhav