Astronauts orbiting the Moon watch an explosion on the surface but hear nothing at all. What explains this?
AThe sound is too quiet to be heard
BThe sound travels too fast to hear
CThere is no medium to carry the sound
DThe explosion made no sound at all
Answer & Solution
Correct answer: C. There is no medium to carry the sound
1. Sound is a longitudinal pressure wave built from compressions and rarefactions.
2. Compressions and rarefactions can only exist where there are particles to be squeezed and spread.
3. Sound waves therefore need something to travel through.
4. Between the Moon surface and the spacecraft there is a vacuum with almost no particles.
5. With no medium there is nothing to carry the disturbance, so nothing reaches the astronauts.
6. Light needs no medium, which is why the explosion can still be seen.
7. Loudness is not the issue, because even a very loud sound cannot cross a vacuum.
_Source: Siyavula Physical Sciences Grade 10 (Everything Science, CC BY 4.0), Chapter 10: Sound_
Related questions
Two identical sirens sound, one on a parked car and one on a car speeding towards you. WhaA singer's note makes a piano string sound without touching it. What is happening?Why does the speed of sound in a gas change with temperature?Sound reaches you faster through a steel rail than through the air. Why?A sound is described as periodic. What does that say about the particles of the medium?A vibrating guitar string makes a sound. What does it do to the surrounding air?Why can sound not travel across a vacuum?You drive an oscillating object far above its natural frequency. What happens to the ampli