Paper cups, needles, tapes, cardboard, scissors.
experimental procedure
Step 1: Fix the needle at the bottom of the paper cup near the cup bottom, with the needle tip passing through the lower edge of the cup wall and the needle in the center of the cup bottom. Pay special attention not to break the bottom of the cup;
Step 2: Stick the needle firmly with adhesive tape;
Step 3: Cut the cardboard into small squares of 1 cm× 1.5 cm (or other axisymmetric shapes with similar size);
Step 4: drill a small hole in the center of the paper with a sharp object (such as a pen tip ~) slightly thicker than the needle;
Step 5: hang the paper on the needle tip;
Step 6: Cut off a section of adhesive tape and stick it on the needle tip to prevent the paper from falling off;
Keep sounding at the paper cup, and constantly adjust the volume and tone. With the right sound, you can see the paper turning like a windmill ~
Experimental principle:
The sound we make is made by vibrating the vocal cords, and the vibration of the sound can be transmitted to the paper cup through the air. The bottom of the paper cup vibrates with the sound, and then it is transmitted to the needle in close contact with it, and then it is transmitted to the paper by the needle. With proper vibration, the paper begins to rotate.