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3 years ago

Humans first appeared during the _____.

2 answers:

8 0

Humans first appeared during the Quaternary period. The Quaternary or Neozoic period develops in the Cenozoic era, which extends from 2,588 million years ago to the present. The Quaternary is divided into two periods. The Pleistocene, the first and longest period of the period, was characterized by the cycles of glaciations and the appearance of the first humans (homos habilis); this period extended from 2,588 million years to 10,000 years BC The Holocene, the second epoch of the period, was characterized by the end of the glaciation and the emergence of human civilization; this period extends from 10,000 years BC to the present.

sergeinik [125]3 years ago

6 0

your answer is Quaternary period

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Which of the following characteristics is a quality of a socially developing economy?

tensa zangetsu [6.8K]

Answer:

Explanation:

Got it right

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3 years ago

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When changing a tire sized 195/75 R15 to a 5 percent lower profile, the correct tire size would be _____

valentinak56 [21]

Answer and explanation:

When you are changing a car tire, the most important thing is to keep the total diameter as equal as possible.

The total car tire diameter can be calculated as:

$D_{tot orig}=\frac{195 \cdot 75}{2540 \cdot 2}+15''=26.5''$

The profile of this tire is 75 (the higher/taller relation), therefore a 5 percent lower profile would be:

pr=0.95·75=71.25

The problem is that the profiles are normalized and the nearest profile available is 70.

If we take a theorical tire with a profile of 71.25:

$D_{tot orig}=D_{new}\\\frac{195 \cdot 75}{2540 \cdot 2}+15''=\frac{X \cdot 71.25}{2540 \cdot 2}+15''\\X=205.26$

The theorical tire size should be 205/71 R15.

If we look for a real tire size, we should look for a tire with a diameter nearest to 26.5'' and a profile of 70.

The best option for real tire size is: Tire 225/70 R14 (wheel diameter of 26.4'') or 205/70 R15 (wheel diameter of 26.3'').

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4 years ago

A beam of light, initially travelling in the air, strikes water surface at an angle of 24.5° with the normal. If the speed of li

kykrilka [37]

Answer:

Explanation:

n = 3.00e8/2.22e8 = 1.35

1.00sin24.5 = 1.35sinθ

θ = 17.9°

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3 years ago

Is the following chemical equation balanced? MgI2 + Br2 MgBr2 + I2 yes no

Brums [2.3K]

Yes

Explanation:

This chemical equation:

$Mg I_2 + Br_2 \rightarrow Mg Br_2 + I_2$

is balanced, because the number of atoms of each element is the same on the reactant side and on the product side. In fact:

- Mg: one atom on the left, one on the right

- I: 2 atoms on the left, and 2 on the right

- Br: 2 atoms on the left, and 2 on the right

So, the reaction is balanced.

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3 years ago

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scientific endeavor is a purely positive action that does not sometimes cause potentially harmful results.

Naya [18.7K]

I think that the question is simply asking whether the statement is correct.

The statement is wrong! The scientific endeavor (the work of the scientists, the pursue of knowledge) can be potentially harmful. For example, many tests of human medicine have to be performed on animals, and often the medicine causes great suffering in the animals (and gets rejected for testing on humans).

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3 years ago