Why does a straw crumple when inserted into a potato?

What you need:

A couple of straws and a boiled potato

What you do:

Hold the potato with one hand. Cover the top end of the straw with the forefinger of your other hand. Then, keep the straw perpendicular to the potato, and push it in. Repeat a couple of times, gently and with force and observe any change in the straw.

Next, insert another straw in the potato but without blocking the upper end with your finger. Repeat this too a couple of times and observe if the straw undergoes any change in shape.

What you find:

The straw remains rigid when you block its top end but gets crushed when you don’t cover it.

Why does this happen?

As both ends of the straw are open, air passes through it constantly. When you hold the straw perpendicular to the potato and cover its top end with your finger, the air inside the straw gets trapped. It cannot escape from top because you are blocking it with your finger. It can’t escape from the bottom because of the potato. This is why it remains rigid. When you insert the straw without blocking its top end, air is able to escape and that’s why the straw crumples.

Picture Credit : Google

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