World Population Clock
Singing glasses video
Why does that happen?
You will have noticed that the pitch of the note goes up as the amount of water in the glass decreases.You vibrate both the glass and the water at a low frequency by running your finger around the rim of the glass. As you do this, your finger sticks and slides around the edge and this action causes the vibrations. You could see that it was both the glass and the water vibrating as you could see the ripples on the surface of the water. The vibration you put in was just the right frequency to get the whole glass and water vibrating. Everything has a frequency that it naturally likes to vibrate at. This is called its resonant frequency. It occurs when we put in just the right amount of energy for an object (and it can be any object) to get vibrating. The pitch of the note went up when you drank some water because there was less stuff (mass) to vibrate. This means that the resonant frequency is a bit higher and you end up with a higher pitch note.
Reminders:
*Tutorial tomorrow & Friday
*Chapter 6 Test on Friday
Today's agenda:
Review answers to 6.3 worksheets
Chapter 6 Biology Jeopardy review game
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