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 686 Hz note. What is the note's wavelength in air, Bo?

   0.5 m
3. 3.

   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. 4.

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

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

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

   • Agree: amplitude is crest to trough
   • Disagree: they carry energy, not the water
   • Agree: bigger ripples move faster
   • Agree: the water rides along with each ripple
6. 6.

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

   • Agree: amplitude is the full height
   • Disagree: it is rest line to crest
   • Agree: and shorter waves have lower frequency
   • Agree: taller waves travel faster
7. 7.

   Pia says a higher-pitched note has a longer wavelength in the same air. Agree or disagree?

   • Agree: higher notes push the air along faster
   • Agree: higher frequency means longer waves
   • Disagree: higher frequency, shorter wavelength
   • Agree: higher notes travel faster
8. 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; dogs and people hear the same sounds
   • Yes; 25,000 is close to 20,000
   • No; it is above 20,000 Hz
9. 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?

   • Sound can't travel in water
   • In air, since air is thinner
   • In water
   • The same in both
10. 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 0 s, since sound is instant
    • About 343 s
    • About 1 s
    • About 2 s