E Learning Task No. 3: Read the given information about sounds. Answer the guide questions at the end of the lesson. Write your answers in your notebook. Have your parents/guardian sign your work. Sound is the energy things produce when they vibrate (move back and forth quickdy). If you bang a drum, you make the tight skin vibrate at very high speed (it's so fast that you can't usually see it), forcing the air all around it to vi- brate as well. As the air moves, it carries energy out from the drum in all direc tions. Eventually, even the air inside your ears starts vibrating and that's when you begin to perceive the vibrating drum as a sound. In short, there are two dif ferent aspects to sound: there's a physical process that produces sound energy to start with and sends it shooting through the air, and there's a sepa- rate psychological process that happens inside our ears and brains, which con vert the incoming sound energy into sensations we interpret as noises, speech, and music. Sound is like light in some ways: it travels out from a definite source (such as an instrument or a noisy machine), just as light travels out from the Sun or a light bulb. But there are some very important differences between light and sound as well. We know light can travel through a vacuum because sun- light has to race through the vacuum of space to reach us on Earth. Sound, however, cannot travel through a vacuum: it always has to have something to travel through (known as a medium), such as air, water, glass, or metal. (Reference: Hewitt, P. et al. Conceptual Physical Science Explorations) 4. Describe the transmission of sound through solids, liquids and gases.
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