They are called mechanical waves
Answer:
There's a video called Drawing Position vs Time Graphs made by MrDGenova that may help you, it's only three minutes long.
Explanation:
Hope that helps, if not, you could tell me what you don't understand and I could try explaining it in further detail.
The density of ice is less than the density of water. C
Planetary Nebula are the outer layers of a star that are lost when the star changes from a red giant to a white dwarf. A star is a luminous globe of gas producing its own heat and light by nuclear reactions (nuclear fusion). They are born from nebulae and consist mostly of hydrogen and helium gas.
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