Harmonic Knife (Funky Physics Experiments)

You will need:

1. Butter knife
2. Pen or any other object
   to hit the knife with

Understand the science of sound and music, by trying out a simple experiment and collating your result.

INSTRUCTIONS

1. Holding the knife in various places along the length of the handle, strike it gently with a pen and hear the variations in sound.
2. Starting closer to the centre, hold the knife near the base of the blade in the middle and strike the blade with the pen.
3. Next, hold the handle farther out, and strike the blade with the pen.
4. Lastly, hold the knife handle at the end, and hit the blade with the pen.
5. Record all the differences in noise.

RESULT

Holding the knife near the blade, closer to the centre, will make the sound produced by hitting the pen on it, very dull; it is almost like a thud. But the sound of the pen hitting the blade becomes clearer and rings better as your hold on the handle moves outward towards the tip of the handle. This is a result of the vibrations produced by the blade along the anti-nodes (areas where the knife moves when it vibrates), which will make the air around it vibrate. By holding the knife in a place where it vibrates (like closer to the centre), the vibration transfers from the knife to the hand, and it does not produce any sound.