Lesson 11 — 1st online lesson

• speed calculations
• Voortgezet speciaal onderwijs
• Leerroute 2

Sound calculations

Learning goals

• Learn to calculate the speed of sound using distance and time
  

• Learn to calculate the speed of sound using wavelength and frequency
  

Two formulas to calculate the speed of sound

Two formulas to calculate the speed of sound

speed=​time​​distance​​

Two formulas to calculate the speed of sound

speed=​time​​distance​​

speedofsound=wavelength⋅frequency

speedofsound=wavelength⋅frequency

• Frequency: The amount of waves in one second

• Wavelength: the length of one wave
  

• Frequency • wavelength = the distance traveled in one second
  

speed=​time​​distance​​

v=​t​​d​​

• v: speed in m/s
  
• d: distance in m
  
• t: time in s
  

speed=​time​​distance​​

v=​t​​d​​

• v: speed in m/s
  
• d: distance in m
  
• t: time in s
  

3=​2​​6​​

• v_s: the speed of sound (m/s)
  
• λ: wavelength (m)
• f: frequency (Hz)
  

speedofsound=wavelength⋅frequency

v_s = λ • f

• v_s: the speed of sound (m/s)
  
• λ: wavelength (m)
• f: frequency (Hz)
  

speedofsound=wavelength⋅frequency

v_s = λ • f

6=2⋅3

 Someone makes a yell in a mountain valley. The closest mountain is at a distance of 411,6 meters away from them. The speed of sound in air is 343 m/s.  How long will it take before they hear the echo?

1. 4,8 seconds
2. 3 seconds
3. 5 seconds
4. 2,4 seconds

Given:

• v = 343 m/s
• d = 411,6 m x 2 = 823,2 m

Asked:

• How long will it take before they hear the echo?

Formula:

•  v = d/t     —>       t = d/v

Calculation:

•  t = 823,2 / 343 = 2,4 s

 Someone makes a yell in a mountain valley. The closest mountain is at a distance of 411,6 meters away from them. The speed of sound in air is 343 m/s. How long will it take before they hear the echo?

A sound wave traveling through copper has a frequency of 400Hz. It has a wavelength of 5,65m. 

Calculate the speed of sound in copper.

1. 70.8 m/s
2. 600 m/s
3. 2260 m/s
4. 2460 m/s

Given:

• Frequency = 400 Hz
• Wavelength = 5.65 m

Asked:

• Calculate the speed of sound in copper

Formula:

•  Speed of sound = wavelength • frequency

Calculation:

•  Speed of sound = 400 x 5,65 = 2260 m/s

A sound wave traveling through copper has a frequency of 400 Hz. It has a wavelength of 5,65 m. Calculate the speed of sound in copper.

Learning goals

• Learn to calculate the speed of sound using distance and time
  

• Learn to calculate the speed of sound using wavelength and frequency