Creating Sound Through Vibrations

Research Questions:

• How do vibrations create sound?
• How can the pitch and volume of a sound be changed?

Sounds are all around us. We hear sound from the radio, when we drop something on the floor, and when we ring a doorbell. Where does sound come from though? Sound comes from vibration. Vibrations are rapid, back-and-forth movements and can be caused by plucking guitar strings, beating a drum, or by simply flicking a paper clip or rubber band. Sounds can vary in volume and pitch based on how the vibrations are created.

Materials:

• Ruler
• Rubber bands of different lengths and thickness
• Tuning fork

Experimental Procedure:

1. Place a ruler on a table with most of it sticking out over the edge. Firmly hold the part on the desk while plucking the free end of the ruler with the other hand. Watch and listen closely. Record your observations. (See sample chart below.)
2. Have an adult carefully stretch one of the rubber bands while you pluck it. Record your observations. 
3. Repeat this step with rubber bands of varying lengths and thickness. Record your observations.
4. Carefully strike the tuning fork against the bottom heel of your shoe. (Note: Striking a tuning fork against something hard can damage the tuning fork. This is why you should strike it on the rubbery sole of your shoe.) What do you observe? Record your observations. 

5. What would happen to the volume if you plucked each object a bit harder? Try it!  

Terms/Concepts: Sound; Vibration; Pitch; Volume

References:

a.    http://www.sciencekidsathome.com/science_topics/what_is_sound.html b.    http://www.sciencekids.co.nz/sciencefacts/sound.html