Can some one answer 4 for me and if u can't read it it says what can scientists learn by studying layers of rock in the earth

They can learn more about Earth's history and environment. Studying rocks can also help scientists discover clues about what Earth was like millions of years ago. That can help them comprehend on our effects on the environment and its probable effects on humans. 

Scientist study earthquakes and rock formations because they can tell you what is inside the Earth and what kinds of fossils there are.

    5.5 n======    assuming that      we have      m = 0.145 kg    a = 38 m/s²therefore    5.51 n, but two significant figures.final answer: 5.5 n

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