Free Speed of Sound MCQs with Answers
2 Speed of Sound MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
2 questions
1. The speed of sound is greatest in
- A. air
- B. water
- C. steel
- D. vacuum
Explanation: Sound travels fastest in solids because their particles are closely bound and pass on a disturbance quickly, giving about 5000 m per second in steel against 1500 in water and 340 in air. It cannot travel through a vacuum at all, since it needs a material medium. Light behaves in exactly the opposite way, travelling fastest in a vacuum.
Correct answer: steel2. The speed of sound in air increases when
- A. the pressure alone increases at constant temperature
- B. the temperature increases
- C. the humidity falls
- D. the frequency of the sound increases
Explanation: Speed rises by roughly 0.61 m per second for every degree Celsius, because hotter molecules move faster and transmit the disturbance more quickly. Changing pressure alone has no effect, since density changes in the same proportion and the two cancel. Speed is also independent of frequency, which is why a distant band is heard in tune rather than smeared out.
Correct answer: the temperature increases