Overview: Parents can help their students with this exercise using readily available items to figure the rough speed of sound. Incorporate this into your regular lessons on sound.
Teacher Preparation: Optional hand-out sheet describing the procedure below.
* Discuss the phenomenon of sound traveling much slower than light, hence seeing distant actions before hearing their accompanying sounds.
* Explain how knowing the distance from an action and timing the length of time a sound takes to reach us enables us to calculate the speed the sound is traveling at.
* Brainstorm with students situations where the time delay can be confusing, such as at sporting events or public concerts.
* Brainstorm with students ways they can estimate the speed with their parents. Hint: An automobile is an easy way. Drive from point A to B, using the odometer to go a fixed distance such as a quarter mile or half kilometer. Using a stopwatch (many digital wristwatches have one) clock the time delay of slamming a door.
* Remember to have students do the experiment several times to obtain consistency.
Options/Variations: Discuss the variable of temperature as it affects the speed of sound; at 32F/0C the speed is 1085 feet per second. At 212F/100C the speed is 1268 feet per second.