The ball bounces endlessly…or almost

The ball bounces endlessly…or almost

November 19, 2022 – Yannick Bergeron, chemist


Easy experiment with the most bouncy material In the world do you tempt?

Experiment equipment:

  • affiliate Party balloons
  • scissors
  • A few containers of different sizes: cups, mason jars, salad bowls, etc.
  • affiliate marble metal or glass

Preparation steps

1. Cut off the top of the balloons with scissors.

2. Gently stretch a cut balloon and secure it over the opening of a mason jar. Stretch it tightly to avoid wrinkles. So ! I made a latex potty trampoline! Latex is the material the balloon is made of.

3. Repeat step 2 for other balloons and containers of different sizes.

4. Practice bouncing marbles on the trampoline. Let it fall well into the middle of the membrane to prevent it from bouncing around in all directions.

5. Drop the ball from different heights.

6. Now bounce your marbles on potty trampolines of different sizes. what do you notice?


what’s going on ?

When the ball falls on latex membrane, extending downward, then suddenly resuming form by dropping the ball upwards. Then, Earth’s gravity causes it to fall back onto the membrane. The ball bounces and so on.

However, the height of the bounces decreases over time. why ? Speed ​​gives energy to the ball. By expanding, the latex absorbs this energy. Then, it regains its shape, and returns it to the ball to propel it into the air. Except that he loses a small part of it! The ball no longer has enough energy to reach its previous height. Therefore, each retracement is always lower than the previous one.

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with you ? It depends on the material the ball is bouncing on. The latex membrane makes the ball take off again at 97% of its arrival speed. they say that recovery coefficient from a membrane latex is 0.97. It is one of the highest rates in the world. With this coefficient, the mathematical formula makes it possible to calculate the bounce height of the ball. For the latex membrane, it is 95% of the previous height.

On wood, this coefficient will be about 0.50. The ball will take off again at half (50%) of the speed it reached and will reach a quarter (25%) of the previous height.

The ball that falls from above picks up more speed and accumulates more energy. So it bounces higher and longer than the ball falls down.

What if the diameter of the trampoline potty changes? No difference. Regardless of their diameter, latex veneers have the same recovery coefficient. Provided that they are stretched in the same way, and that the balls are bounced in the center of the membrane.

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About the Author: Octávio Florencio

"Evangelista zumbi. Pensador. Criador ávido. Fanático pela internet premiado. Fanático incurável pela web."

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