Sound- Post Assessment

An echo-sounder on a ship produces a pulse of sound. The echo is received by the echo-sounder after two seconds.

The speed of sound in sea-water is 1500 m/ s. What is the depth of the sea-water below the ship?

• 750 m

• 1500 m

• 3000 m

• 6000 m

What can be heard by the human ear?

• a whistle emitting a wave of frequency 50 kHz

• a bat emitting a wave of frequency 30 kHz

• an insect emitting a wave of frequency 300 Hz

• a vibrating spring emitting a wave of frequency 5 Hz

A student claps once when standing 100 m away from a large wall. The speed of sound in air is 330 m/ s. How long after clapping does the student hear an echo?

• 0.3 s

• 0.61 s

• 1.7 s

• 3.3 s

A tuning fork is marked with the number 320. 320 This indicates the size of the frequency. What does this mean?

• The length of the tuning fork is 320mm.

• The note from the tuning fork will last for up to 320s

• The sound waves produced by the tuning fork travel at 320m/ s.

• The tuning fork vibrates 320 times every second.

A student wishes to measure the speed of sound in air. She plans to measure the time between making a sound and hearing the echo from a cliff. She will use the equation: speed = distance / time . Which type of sound should she make and which distance should she use in her calculation?

• A

• B

• C

• D

When the volcano Krakatoa erupted in 1883, it was heard 5000 km away. Which statement about the sound from the volcano is not correct?

• If such a loud sound were to be made today, an astronaut orbiting in space (a vacuum) at a height of 400km could hear it.

• People further from the volcano heard the sound later than people nearer to the volcano.

• The amplitude of the sound waves would have been smaller further from the volcano.

• The sound was very loud because a lot of energy was transferred to vibrations of the air.

Some sound from a loudspeaker at P travels directly to Q. Sound also reaches Q after being reflected from a wall at R. The speed of sound is 330 m/ s. What is the difference in time for a sound to travel from P to Q by the two routes?

• 6/330 s

• 16/330 s

• 6 x 330 s

• 16 x 330 s