unit 9

 

Continuing with the topic of waves, today we learned about sound waves. A few key ideas we learned, were that object want to vibrate, and that noise is a sound that is incoherent. Also, sounds need a medium to travel through.
Using a tuning fork, we did multiple labs showing us how sound travels. The average human can hear about 20 Hz - 20,000 Hz. Animals who can hear higher frequencies are called ultrasonic, whereas the opposite, hearing lower frequencies are called infrasonic. 

In this picture that was taken 5-6 years ago, I am with the cutest water mammal, the dolphin! Out of curiosity, I looked up the range of frequencies they can hear. I found that it was a much bigger range (to no surprise), 250 - 150,000 Hz!

Using the beautiful creature, I created a sample problem that shows how to find the frequency, given the speed and wavelength.
If a wave has a wavelength of 2.17 meters and the speed of sound in water is 923,580 m/s, what is the frequency a dolphin hears in this water?

V= ƒλ
92,580 m/s = f (2.17m)
f = 42,664 Hz, 42.7 kHz