Lesson 11 — 5.6 + 5.7 Echoes

• Sound
• Middelbare school
• havo, vwo
• Leerjaar 2

Echoes

This lesson

• Echoes
  
• Echolocation
  
• Simple calculations
• Traveling faster than sound
  

Learning goals

• Explain in your own words how echoes work
• Describe how echo location works
• Be able to do calculations involving echoes and echo location
• Explain how the mach system works

Echoes

Echo location

Calculation exercise

A man has set out the find the deepest well in the world. Once he found it he clapped his hands above it. He timed how long it took before he heard an echo. It took 71.4 seconds.

 a) How does this help him find out how deep the well is?

b) Calculate how deep the well is.

Calculation exercise

Dolphins can make sounds with a frequency as low as 0.2 Hz and as high as up to 150.000 Hz. A dolphin makes use of echo location. He sends out a signal, with fish floating 240 meters away.  It takes 0.32 seconds before he hear the echo. The wavelength of the sound wave he produced is 0.01875 m. Calculate the frequency of this sound wave.

Traveling faster than sound

Mach 1, Mach 2, Mach 3

• Mach 1: traveling at 343 meters per seconds
  
• Mach 2: traveling at 686 meters per seconds
  
• Mach 3: 1029 meters per seconds
  
• The fastest skydiverer, Felix Baumgartner, traveled at mach 1.1, how fast did he fall?
  

Good luck studying for the test!

Learning goals

• Explain in your own words how echoes work
• Describe how echo location works
• Be able to do calculations involving echoes and echo location
• Explain how the mach system works