Why does paper make noise when crumpled? © Getty Images

Why does paper make noise when crumpled?

Paper makes a handy noise maker, but that requires a lot of energy.

Asked by: Ronald Pirani, US

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It doesn’t take much energy to bend paper, but crumpling it demands injecting so much energy into the fibrous structure of the paper that it’s not merely bent but is permanently deformed, creating sharp creases. Researchers at the University of Chicago showed that such creases form suddenly, and release some of the energy injected in a surprisingly loud burst of noise.


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