Physical Science Homework Problems PHSC P112

Richard Goode

Chapter 5 Sound and Waves

Problems

1.  An insect floating on the water generates waves at a rate of 4 waves each second with a wavelength of 1.5m. What is the period of the waves? What is the velocity of the waves?

T = 0.25s

v = 6 m/s

2.  What is the wavelength of a 15,000hz sound if the air temperature is 25.0 °C?

v = 346 m/s

λ = 0.023 m

3.  Ultrasound frequencies are very high. What is the wavelength of an ultrasound frequency of

2.0 X 107hz in air?

v = 343 m/s

λ = 1.715 x 10-5m

4.  How long does it take a sound of thunder to reach you if you see lightening that is 250m away?

v = 343 m/s

t = 0.73 s

5.  An echo is heard from a building 1.5s after you shout “hello”. How far away is the building if the air temperature is 22 °C?

v = 344.2 m/s

t = 0.75 s (one way)

d = 258 m

6.  A sonar signal is sent from a ship and the signal is returned 2.75s later. How deep is the ocean if the speed of sound in seawater is 1,500 m/s?

t = 1.375 s (one way)

d = 2063 m

7.  A sound wave travel through steel. If the wave has a frequency of 600hz and a wavelength of 9.0m, what is the speed of sound in steel?

v = 5400 m/s

8.  What is the speed of sound if the air temperature is”

  1. 0.0°C v = 331 m/s
  2. 20.0°C v = 343 m/s
  3. 40.0°C v = 355 m/s
  4. 80.0°C v = 379 m/s

Thought Questions

  1. What is a wave?
  2. What does a wave transmit from one place to another?
  3. Why do astronauts use radio waves on the moon to communicate with each other?
  4. Explain why sound waves travel faster in warm air than in cold air.