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3 years ago

Humans first appeared during the _____.

2 answers:

8 0

<span>Humans first appeared during the Quaternary period. <span>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.</span></span>

sergeinik [125]3 years ago

6 0

your answer is Quaternary period

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A projectile is launched from ground level at angle u and speed v0 into a headwind that causes a constant horizontal acceleratio

ale4655 [162]

Answer:

Explanation:

Given

Launch angle =u

Initial Speed is $v_0$

Horizontal acceleration is $a_x=a$

At maximum height velocity is zero therefore

$v_f=v_i-gt$

$0=v_0\sin u-gt$

$t=\frac{v_0\sin u}{g}$

Total time of flight $T=2t=\frac{2v_0\sin u}{g}$

During this time horizontal range is

$R=v_o\cos u\cdot 2t-\frac{a(2t)^2}{2}$

$R=\frac{2v_0^2\sin u\cos u}{g}-\frac{2av_0^2\sin ^u}{g^2}$

For maximum range $\frac{\mathrm{d} R}{\mathrm{d} u}=0$

$\frac{\mathrm{d} R}{\mathrm{d} u}=\frac{2v_0^2\cos 2u}{g}-\frac{4av_0^2\sin u\cos u}{g^2}$

$\frac{\mathrm{d} R}{\mathrm{d} u}=\frac{2v_0^2}{g}\left [ \cos 2u-\frac{a}{g}\sin 2u\right ]=0$

$\tan 2u=\frac{g}{a}$

$u=\frac{1}{2}tan ^{-1}\frac{g}{a}$

(b)If a =10% g

$a=0.1g$

thus $u=\frac{1}{2}tan^{-1}\frac{g}{0.1g}$

$u=42.14^{\circ}$

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3 years ago

At sunset, the sun appears reddish. What is MOST LIKELY the reason for this phenomenon?

Alexeev081 [22]

The only correct statement on the list is choice-A./

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3 years ago

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The difference in the composition of the terrestrial planets and the gas giants can be explained by the different condensation

miv72 [106K]

The inner planets are usually rocky because the gravitational pull is stronger closer to the star or in this case the sun. The dust and rocky particles that are left over after a super nova or in a nebula will tend to orbit closer to a proto-star when a solar system is in its early days. In our solar system these planets are Mercury, Venus, Earth and Mars. Gases are less dense and will be less affected by the pull of gravity because rocky particles have more mass. The outer planets are gas giants formed from clouds of gas that would be further out in the spinning disk around a proto-star.

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3 years ago

What do we mean when we say that motion is relative? What is everyday motion usually related to

Luda [366]

It’s measured in a reference frame that is usually the earth’s surface

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3 years ago

Weight of 9.81 N calculate its mass??

Fudgin [204]

Answer:

0.981kg

Explanation:

As we know,

1kg =10N

So,

mass = 9.81/10 = 0.981Kg

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2 years ago