B. Sound, because everything else sits still and sound waves move
The average distance between galaxies is about one million light years. There are roughly 100 billion galaxies in the observable universe. Another, often-used unit of distance is the parsec. One parsec is approximately 3.26 light-years.
Hello!
Your answer is all of the above. Science is a very broad field, and it is the thing which has engineered most, if not all, of our technology today. Take for example microwave ovens. These could not have been possible without science, as it was science that realized that "microwaves" (a type of wave length) even existed.
Hope this helps!
less than 20 Hz
The frequency of subsonic sound is less than 20 Hz
subsonic sound refers to a sound which has a wave that travels slower than the speed of sound.
- frequency of audible sound: 20 Hz to 20,000 Hz
<u>Thus </u>subsonic sound < 20 Hz
That's pretty easy, have a look :
The only thing you need to do is to find t and the problem is solved.