Energy is extremely useful
As humans have always used energy, in the ancient times it was really only thermal, from burning wood for warmth and preparing food, then people learned to use animal's energy, and things moved on from there, getting into more complex stuff like we have today.
Life without energy from various sources is unimaginable today
You would use a mass spectrometer
Answer: No, the speed of propagation is constant in a given medium; only the wavelength changes as the frequency changes.
Explanation:
<span>B. The model gradually changed as new scientific data was gathered.</span>
