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3 years ago

12

Prompt how does melanin provide protection against skin cancer?

1 answer:

Wittaler [7]3 years ago

4 0

Answer:

absorb , it absorbs it ...

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What is a characteristic of weight <br /><br>I need it please answer it

Marta_Voda [28]

Answer:

Weight is a consequence of the universal law of gravitation

Explanation:

Weight, gravitational force of attraction on an object, caused by the presence of a massive second object, such as the Earth or Moon. Weight is a consequence of the universal law of gravitation: any two objects, because of their masses, attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

8 0

3 years ago

A certain radioactive nuclide decays with a disintegration constant of 0.0178 h-1.

umka21 [38]

Explanation:

Given that,

The disintegration constant of the nuclide, $\lambda=0.0178\ h^{-1}$

(a) The half life of this nuclide is given by :

$t_{1/2}=\dfrac{ln(2)}{\lambda}$

$t_{1/2}=\dfrac{ln(2)}{0.0178}$

$t_{1/2}=38.94\ h$

(b) The decay equation of any radioactive nuclide is given by :

$N=N_oe^{-\lambda t}$

$\dfrac{N}{N_o}=e^{-\lambda t}$

Number of remaining sample in 4.44 half lives is :

$t_{1/2}=4.44\times 38.94$

$t_{1/2}=172.89\ h^{-1}$

So, $\dfrac{N}{N_o}=e^{-0.0178\times 172.89}$

$\dfrac{N}{N_o}=0.046$

(c) Number of remaining sample in 14.6 days is :

$t_{1/2}=14.6\times 24$

$t_{1/2}=350.4\ h^{-1}$

So, $\dfrac{N}{N_o}=e^{-0.0178\times 350.4}$

$\dfrac{N}{N_o}=0.0019$

Hence, this is the required solution.

4 0

4 years ago

Which statement about these cells is correct

Nuetrik [128]

B is correct because most of the cells look the same so it's B

5 0

3 years ago

Total these measurements. Your answer should indicate the proper accuracy. Be sure to include the units in your answer. (Remembe

vivado [14]

Answer:

10

Explanation:

This is tough. The last number 0.2 has only one significant figure. So while the sum of all the numbers is 12.3, you must only leave one sig figure. Rounding to the tenths gives 10.

3 0

4 years ago

Suppose all the people of the Earth go to the North Pole and, on a signal, all jump straight up. Estimate the recoil speed of th

Makovka662 [10]

Explanation:

It is known that relation between velocity and height is as follows.

v = $\sqrt{2gh}$

where, g = acceleration due to gravity = 9.8 $m/s^{2}$

h = height = 0.2 m

Therefore, velocity is calculated as follows.

v = $\sqrt{2gh}$

= $\sqrt{2 \times 9.8 \times 0.2}$

= 3.92 m/s

Also,

$m_{people}v_{people} = m_{earth}v_{earth}$

$v_{earth} = \frac{m_{people}v_{people}}{m_{earth}}$

Putting the given values into the above formula as follows.

$v_{earth} = \frac{m_{people}v_{people}}{m_{earth}}$

= $\frac{6 \times 10^{9} \times 74 kg/person}{6 \times 10^{24} kg}$

= $\frac{444 \times 10^{9}}{6 \times 10^{24}}$

= $74 \times 10^{-15}$ m/s

or, = $7.4 \times 10^{-14}$ m/s

Thus, we can conclude that recoil speed of the Earth is $7.4 \times 10^{-14}$ m/s.

4 0

3 years ago