Lesson 9 — Making calculations

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

P2

Sound

This lesson

• Checking the test of P1
• Sound — calculations
• Studying for tomorrows test

Checking the test of P1

Check your test using the answer sheet of the version of the test you made.

Sound — Calculations

Calculating the speed of sound in different circumstances.

Sound — Calculations

The speed of sound in air is 330 m/s. A person shoots a gun in a mountain valley. 2,5 seconds later he hears the echo. How far away is the nearest mountain from him? Write out your calculation.

The speed of sound in air is 330 m/s. A person shoots a gun in a mountain valley. 2,5 seconds later he hears the echo. How far away is the nearest mountain from him? Write out your calculation.

v = 330 m/s

t = 2,5 s / 2 = 1.25 s

 d = v • t = 1,25 x 330 = 412,5 m

v=​t​​d​​

d=v⋅t

Sound — Calculations

The speed of sound in air is 330 m/s. A person shoots a gun in a mountain valley. 2,5 seconds later he hears the echo. How far away is the nearest mountain from him? Write out your calculation

v = d/t          d = v • t

v = 330 m/s

t = 2,5 s / 2 = 1.25 s

 d = v • t = 1,25 x 330 = 412,5 m

Sound — Calculations

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.

Hint

• frequency: the amount of waves per second
  
•  Wavelength: the length of one wave

Sound — Calculations

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.

• 400 waves per second.
  
• One wave has a length of 5,65 meter.
  
• In one second the sound travels a distance of 440 • 5,65 meters — 400 • 5,65 = 2260 m.
  
• The sound has a speed of 2260 m/s
  

Studying for the test

§5.1 — §5.5