# Fast and Easy Science Fair Projects: Look at the Sound

## Light speed faster than sound speed

Purpose: Prove that sound travels much slower than light through the medium of air.

Overview: Lightning streaks across the sky. Wait! It's only then you hear the rumble of the thunder. You hear a jet plane flying high overhead. You look up immediately, but it's already way past you. You're at a baseball stadium, far from home plate. The batter's ready. There's the pitch! It's a hit, and the ball starts to soar. Then, you hear the crack of the ball against the bat!

Why do we see things before we hear them? Could it be because speed of light is faster than speed of sound through the air? (Actually, light travels 186,000 miles per second, so when something happens we see it almost instantly. Sound travels through the air much more slowly, only about 1,100 feet per second - 764 miles per hour at 32 degrees Fahrenheit - slightly faster at higher temperatures.)

Hypothesis: We can prove that sound travels more slowly than light through air.

You need:

• An adult with a car
• A straight, mile-long, open stretch of road

Procedure: Find an open stretch of road at least a mile long. Some evening, as you stand safely to the side of the road, have an adult with a car drive one mile away, then turn the at around and turn the headlights on and "beep" the horn at the exact same time. Do you see the flash of the headlights before you hear the sound of the horn?

The Constants are the distance and the time the headlights are turned on and the horn is sounded. The Variable is the time it takes for the light and sound to go from car to you.

Results and Conclusion: Write down the results of your experiment. Come to a conclusion as to whether or not your hypothesis was correct.

Something more:

1. Does wind direction have an effect on the travel of sound through the air?

2. Does sound take so long to reach your ears that, in the above experiment, the driver could blink the lights on and off several times before you even hear the horn?

3. What things can transmit sound but not light, or light but not sound? Think about a supernova, a railroad track.

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Seakay 5 years ago from Florida

I always hated science fair projects in school! Mine always looked awful compared to the ones the parents did for their kids to present! One year, I couldn't even understand the project, it was so complicated. Hope his Dad got an A! LOL

Don Ship 5 years ago Author

Haha, I always liked doing Science Projects at School and at home! I still do, when I get time! Lol, at least you tried something on your own. That's great and trying is what that counts! Haha. He sure must've! LMAO! :D