Why Does a Ruler Buzz When You Flick It Off the Edge of a Desk?

What Crafty Clover says in this video

Intro

Hi there, curious minds! I'm Crafty Clover! Let's discover something amazing. Why does a ruler buzz when you flick it off the edge of a desk?

The Big Idea

A flicked ruler bends and springs back, over and over, and that makes a buzz! Each wiggle pushes on the air and makes a tiny sound. The wiggles come so fast that your ears hear one buzz, not separate bumps.

Bend and Spring

Step one: bend and spring. When you flick the free end, it bends down, then springs back up. It overshoots a little, so it keeps going back and forth.

Air Gets Pushed

Step two: the air gets pushed. Every wiggle gives the air next to the ruler a tiny push. Those pushes spread out as a sound wave toward your ears.

Many Wiggles

Step three: many wiggles blend together. The ruler wiggles dozens of times each second. That is fast enough that your ears hear a buzz instead of separate bumps.

A Closer Look

Let's take a closer look! Half of the ruler hangs over the edge. A flick gives the free end a starting push. It wiggles up and down very fast. And the wiggle becomes a buzz.

Quick Facts

Quick facts! A harder flick makes a bigger wiggle. A bigger wiggle makes a louder buzz. Pressing the ruler down firmly stops the vibration, and the buzz stops. Keep the ruler away from your face, and ask a grown-up to help.

Think Like a Scientist

Now, your mission! Hold a ruler flat on a desk with half of it hanging over the edge. Gently flick the end and listen, then flick a little harder. What changes? Keep the ruler away from your face. Share what you discover with a grown-up.

Outro

A buzzing ruler is a fast wiggle in action. Science is amazing! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!