SoundIB MYP Physics: Mind map

Exam questions on Sound

1. In a science-fiction film, a spacecraft explodes in the vacuum of space and the audience hears a loud bang. A physics teacher says this could not happen in real life, although a crew member inside the spacecraft could hear a tapping sound travelling through the metal hull.
   Explain why the bang could not be heard in space.2 marks
2. A student records two notes on a guitar. Note X has a frequency of 220 Hz and is plucked firmly. Note Y has a frequency of 440 Hz and is plucked gently. She then blows a dog whistle that makes sound of frequency 30 kHz. Her dog reacts to the whistle straight away but she hears nothing.
   Explain why the dog can hear the whistle but the student cannot.2 marks
3. Two students measure the speed of sound in air. Hannah stands 85 m from a large, flat wall and claps her hands once. Raj, standing next to her, starts a stopwatch at the clap and stops it when he hears the echo. He repeats this five times and records the times 0.50 s, 0.54 s, 0.48 s, 0.52 s and 0.51 s.
   Calculate the mean time and use it to calculate the speed of sound in air.3 marks