Science Assessment

Students should know that:

1. Energy is transferred when a molecule of a vibrating object collides with a molecule of an adjacent medium. 
2. As sound travels through a medium, the molecules that make up the medium are displaced and move in a back-and-forth wave-like motion, which can cause the molecules of the medium to collide with one another.
3. The collisions between molecules move through the medium as a wave, and when the sound wave reaches the receiver, the molecules of the medium collide with the molecules of the receiving object, transferring energy to the receiver in the process.
4. In the medium, the closer together the molecules are to each other, the more frequent the collisions, the faster the sound travels and the faster energy is transferred.  Therefore, energy is transferred by sound faster through solids than through liquids or gases, and faster through liquids than through gases.
5. The greater the displacement of the molecules of the medium (amplitude of the sound) the greater the amount of energy transferred. The greater the amplitude the greater the loudness.
6. The reason that the amount of energy that can be transferred by sound decreases the farther away the source of the sound is from the receiver is that some energy is absorbed by the molecules of the medium as the sound passes through.
7. Low frequency sound travels farther through a given medium than high frequency sound because there are fewer collisions of the molecules and, therefore, less energy is absorbed by the medium as the low frequency sound travels to the receiver.  Therefore, the higher the frequency the lesser the amount of energy transferred to the receiver. The pitch of the sound is related to the frequency.

Boundaries:

1. Items do not ask students to calculate how much energy is transferred by conduction in a particular situation. The sub-ideas above describe semi-quantitative relationships.
2. Assessment items are limited to one vibrating object producing a sound wave.