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DanielleElmas [232]
3 years ago
10

Why is there so much variation in human skin coloration? a. This occurred because humans underwent natural selection, which resu

lted in traits that conferred advantages to humans becoming fixed in populations. b. This occurred because alleles that are harmful in one environmental context may be beneficial in another. c. This occurred because humans are found in areas that range from high-UV-light environments to low-UV-light environments. d. This occurred because skin coloration results in different advantages depending on the levels of sun in the region.e. All of these.
Physics
1 answer:
Arlecino [84]3 years ago
5 0

Answer:

<u>e. All of these.</u>

Explanation:

  • The skin in humans ranges from darkest to the lightest color, as a result of genetic makeup, exposure to the sun rays, skin pigmentation may be either due to the evolutionary process of natural selection, and it may be due to the biochemical effects of the UV rays.
  • As the pigment in the skin of humans is affected by the content of melanin in the body that causes the determination of skins cells of the darker colored humans, and the light skin is determined by the bluish-white tissues under the dermis and the hemoglobin.
  • The emergence of skin pigments dates back to 1.2 billion years ago. When the harsh climatic conditions drove the early humans into arid and open landscapes. In general, the people living near to equator have darkly pigmented than those living in poles are lightly pigmented.
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What is the magnitude of the torque about his shoulder due to the weight of the ball and his arm if he holds his arm straight ou
Lubov Fominskaja [6]

Answer:

The torque about his shoulder is 34.3Nm.

The solution approach assumes that the weight of the boy's arm acts at the center of the boy's arm length 35cm from the shoulder.

Explanation:

The solution to the problem can be found in the attachment below.

6 0
3 years ago
Alex pushes on a 2.0 kg book, resulting in a net force of 6.0 N on the book.
Yakvenalex [24]

Answer:

<h2>3.0 m/s²</h2>

Explanation:

The acceleration of an object given it's mass and the force acting on it can be found by using the formula

a  = \frac{f}{m}  \\

From the question we have

a =  \frac{6}{2}  \\

We have the final answer as

<h3>3.0 m/s²</h3>

Hope this helps you

4 0
3 years ago
A 750 g air-track glider attached to a spring with spring constant 14.0 N/m is sitting at rest on a frictionless air track. A 20
alexandr402 [8]

Answer:

the amplitude of  the subsequent oscillations is 0.11  m

the period of the subsequent oscillations is 1.94 s

Explanation:

given Information:

the mass of air-track glider, m_{1} = 750 g = 0.75 kg

spring constant, k = 13.0 N/m

the mass of glider, m_{2} = 200 g = 0.2 kg

the speed of glider,  v_{2} = 170 cm/s = 1.7 m/s

the amplitude of  the subsequent oscillations is A = 0.11  m

according to mechanical enery equation, we have

A = \sqrt{\frac{m_{1} +m_{2} }{k} }v_{f}

where

A is the amplitude and  v_{f} is the final speed.

to find v_{f}, we can use momentum conservation lwa, where the initial momentum is equal to the final momentum.

P_{f} = P_{i}

(m_{1} +m_{2} )v_{f} = m_{1} v_{1} +m_{2}v_{2}

v_{1} = 0, thus

(0.75+0.2)v_{f} = (0.75)(0)+(0.2)(1.7)

0.95 v_{f} = 0.34

v_{f} = 0.36 m/s

Now we can calculate the amplitude

A = \sqrt{\frac{0.75 +0.2 }{10} }0.36

A = 0.11  m

the period of the subsequent oscillations is T = 1.94 s

the equation for period is

T = 2π\sqrt{\frac{m_{1}+m_{2}  }{k} }

T = 2π\sqrt{\frac{0.75+0.2  }{10} }

T = 1.94 s

7 0
3 years ago
A law enforcement officer in an intergalactic "police car" turns on a red flashing light and sees it generate a flash every 1.2
butalik [34]

Answer:

The velocity of the police car relative to earth is v_{rel} = 2.51\times 10^{8} m/s

Given:

time for flash generation of the inter galactic police car, t = 1.2 s

time between flashes as measured from earth, t' = 2.2 s

Solution:

Utilising Einstein's equation for time dilation to calculate the velocity of the police car, the equation is given by:

t' = \frac{t}{\sqrt {1 - \frac{v^{2}}{c^{2}}}}                                (1)

where, c = speed of light in vacuum = c = 3\times 10^{8}

re arranging eqn (1) for velocity, v:

v_{rel} = c\times \sqrt {1 - (\frac{t}{t'})^{2}}                               (2)

Now, from eqn (2)

v_{rel} = 3\times 10^{8}( \sqrt {1 - (\frac{1.2}{2.2})^{2}})

v_{rel} = 3\times 10^{8}\times 0.838

v_{rel} = 2.51\times 10^{8} m/s

3 0
3 years ago
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