Do you think it is possible to make a coin swirl on its own, that too inside a balloon? Check out this cool experiment where you get to see a coin hoola hooping inside an inflated balloon. You could try this experiment with other small objects such as nuts, beads etc. So, get ready for the coin in balloon experiment.
Materials Required
Small coin – 1
Medium-sized balloon – 1 (transparent or translucent)
Steps to follow
- Insert a small coin into the opening of the balloon and push it all the way inside.
- Blow the balloon and tie the end.
- Hold the upper portion of the balloon and start rotating it with some force. You’ll observe that the coin has started moving in circles inside the balloon, along the inner surface.
- After a while, stop rotating the balloon and bring it to a steady state.
- What do you observe? You can see the coin still dancing around in the balloon.
What we learn
As the coin is still in motion even after the balloon has stopped, we can understand that there are some forces acting on it. The coin was set in motion by the initial force provided by the rotation of the balloon, and the shape of the balloon restricted the movement of the coin to a circular path.
So, let’s find out what other forces are acting on the coin once it starts moving. There is a slight frictional force between the edge of the coin and the surface of the balloon, which ultimately stops the motion of the coin.
But, the force that keeps the coin moving in circles till it stops is what is more interesting! This force is known as the centripetal force. It keeps the object moving in a circular path and pulls the object towards the center of the path. So, the coin keeps moving in circles till it is stopped by the villainous frictional force!
Can you think about some other ‘universal’ circular motion? Yes, you got it right. It’s the circular orbiting movement of the planets around the sun. It’s the sun’s gravitational pull that keeps them circling around.
Did you enjoy this experiment? Explore our Experiments section and find a lot more.
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