Answer:
your answer would be D because the waves results from back n forth vibrations of the particles of the medium throught which the sound waves is moving .
Answer:
It's used to indicate pressure
Answer:
3 m/s
Explanation:
Average Speed = 
Plug in the numbers, it will be (6m + 3m) divided by (2s + 1s), which is 9m/3s, which equals to 3m/s.
Answer:
D. 2.5 Hz
Explanation:
Frequency = speed of wave / wavelength
= 335 /140 ( from graph)
= 2.4
I think its Mercury because it's the closest to the sun.