Wavelength, amplitude and frequency

Answer Key - Grade 8 Science Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   Sound travels about 343 m/s in air at 20 °C. A speaker plays a 343 Hz note. What is the note's wavelength in air, Ari?

   1 m
2. 2.

   Sound travels about 343 m/s in air at 20 °C. A speaker plays a 245 Hz note. What is the note's wavelength in air, Esme?

   1.4 m
4. 3.

   In the wave graph, which wave carries more energy, Jun?

   • Wave P, since it is faster
   • Wave Q, with the bigger amplitude
   • Wave P, with the longer wavelength
   • Both the same, since they share a rope
5. 4.

   In the wave graph, which wave has the higher frequency, Kira?

   Use the picture in question 3.

   • Wave P, with the longer wavelength
   • Both the same, since they share a rope
   • Wave Q, with the shorter wavelength
   • Neither has a frequency
6. 5.

   In the wave graph, wave P has a frequency of 2 Hz. Both waves move at the same speed. What is wave Q's frequency, Luz?

   Use the picture in question 3.

   • 4 Hz
   • 2 Hz
   • 1 Hz
   • 8 Hz
7. 6.

   Milo says pond ripples carry the pond's water to the edge. Agree or disagree?

   • Agree: bigger ripples move faster
   • Agree: the water rides along with each ripple
   • Disagree: they carry energy, not the water
   • Agree: amplitude is crest to trough
8. 7.

   Noah says a wave's amplitude is its height from trough to crest. Agree or disagree?

   • Agree: amplitude is the full height
   • Agree: and shorter waves have lower frequency
   • Agree: taller waves travel faster
   • Disagree: it is rest line to crest
9. 8.

   People hear sounds from about 20 Hz to 20,000 Hz. A dog whistle plays at 25,000 Hz. Can Ren hear it?

   • Yes, if it is loud enough
   • Yes; 25,000 is close to 20,000
   • Yes; dogs and people hear the same sounds
   • No; it is above 20,000 Hz
10. 9.

    At 20 °C, sound travels about 343 m/s in air and about 1,481 m/s in water. Where does it travel faster, Tala?

    • The same in both
    • In air, since air is thinner
    • In water
    • Sound can't travel in water
11. 10.

    Sound travels about 343 m/s in air. Zee claps while facing a cliff 343 m away. About how long until the echo comes back?

    • About 2 s
    • About 1 s
    • About 343 s
    • About 0 s, since sound is instant