Sound Waves — Drills · Grade 8 Science

Chapter: Waves, Sound & Light

What these drills covers

By the end of Sound Waves you should be able to:

8 questions, multiple choice, numeric and written answer, each with a worked explanation.

Vocabulary used: longitudinal wave, compression, rarefaction, pitch, medium, model, evidence, system boundary, assumption.

Problem 1

Sound is a
  1. transverse wave
  2. longitudinal wave
  3. electromagnetic wave
  4. standing wave only
Answer and explanation

longitudinal wave

Air particles oscillate along the direction the sound travels, making compressions and rarefactions.

Problem 2

Sound cannot travel through
  1. air
  2. water
  3. steel
  4. a vacuum
Answer and explanation

a vacuum

Sound needs particles to transmit the vibration; a vacuum has none.

Problem 3

A higher-pitched sound has a higher
  1. amplitude
  2. frequency
  3. speed in air
  4. wavelength
Answer and explanation

frequency

Pitch corresponds to frequency; loudness corresponds to amplitude.

Problem 4

Sound travels at about 340 m/s in air. How far does it go in 3 seconds, in metres?
Answer and explanation

1020 m

340 × 3 = 1,020 m.

Problem 5

An echo returns after 2.0 s from a cliff, with sound at 340 m/s. How far away is the cliff, in metres?
Answer and explanation

340 m

The sound travels there and back: 340 × 2.0 = 680 m total, so the cliff is 340 m away.

Problem 6

Sound generally travels fastest in
  1. a gas
  2. a liquid
  3. a solid
  4. a vacuum
Answer and explanation

a solid

Particles are closest together in a solid, so the vibration passes along more quickly.

Problem 7

Explain why you see lightning before you hear thunder.
Answer and explanation

Light travels enormously faster than sound — about 300 million m/s against roughly 340 m/s in air — so the light from a flash arrives almost instantly while the sound takes about three seconds for every kilometre. The two are produced at the same moment; the delay is entirely a difference in travel time, which is why counting the seconds estimates the distance.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

Problem 8

A bell is rung inside a jar as the air is pumped out. Describe what happens and what it shows.
Answer and explanation

The sound grows fainter as air is removed and becomes inaudible when the jar is close to empty, even though the bell can still be seen vibrating. This shows that sound requires a material medium to carry the vibration between particles, while light does not, since the bell remains visible throughout.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

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