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OLEGan [10]
3 years ago
8

What happens during the fall in September?

Physics
2 answers:
san4es73 [151]3 years ago
4 0

Answer:

d

Explanation:

8090 [49]3 years ago
3 0

Answer:

During the fall in September, the Sun passes from northern hemisphere towards equator. ... On this day, Sunlight directly falls on the equator i.e. the sun crosses celestial equator. Day time is equal to night time in the two hemispheres

Explanation:

make me brainiest if it helps you

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A tree falls in a forest. How many years must pass before the 14C activity in 1.03 g of the tree's carbon drops to 1.02 decay pe
Illusion [34]

Answer:

t = 5.59x10⁴ y

Explanation:

To calculate the time for the ¹⁴C drops to 1.02 decays/h, we need to use the next equation:

A_{t} = A_{0}\cdot e^{- \lambda t}    (1)

<em>where A_{t}: is the number of decays with time, A₀: is the initial activity, λ: is the decay constant and t: is the time.</em>

To find A₀ we can use the following equation:  

A_{0} = N_{0} \lambda   (2)

<em>where N₀: is the initial number of particles of ¹⁴C in the 1.03g of the trees carbon </em>

From equation (2), the N₀ of the ¹⁴C in the trees carbon can be calculated as follows:        

N_{0} = \frac{m_{T} \cdot N_{A} \cdot abundance}{m_{^{12}C}}

<em>where m_{T}: is the tree's carbon mass, N_{A}: is the Avogadro's number and m_{^{12}C}: is the ¹²C mass.  </em>

N_{0} = \frac{1.03g \cdot 6.022\cdot 10^{23} \cdot 1.3\cdot 10^{-12}}{12} = 6.72 \cdot 10^{10} atoms ^{14}C    

Similarly, from equation (2) λ is:

\lambda = \frac{Ln(2)}{t_{1/2}}

<em>where t 1/2: is the half-life of ¹⁴C= 5700 years </em>

\lambda = \frac{Ln(2)}{5700y} = 1.22 \cdot 10^{-4} y^{-1}

So, the initial activity A₀ is:  

A_{0} = 6.72 \cdot 10^{10} \cdot 1.22 \cdot 10^{-4} = 8.20 \cdot 10^{6} decays/y    

Finally, we can calculate the time from equation (1):

t = - \frac{Ln(A_{t}/A_{0})}{\lambda} = - \frac {Ln(\frac{1.02decays \cdot 24h \cdot 365d}{1h\cdot 1d \cdot 1y \cdot 8.20 \cdot 10^{6} decays/y})}{1.22 \cdot 10^{-4} y^{-1}} = 5.59 \cdot 10^{4} y              

I hope it helps you!

4 0
3 years ago
1.
rusak2 [61]

Answer:

9.6

Explanation:

to convert km to miles multiply by 1.609

7 0
4 years ago
. Friction is a rubbing force that ___________ a spinning yo-yo.
Advocard [28]
The yo-yo speeds up when you rub it
3 0
3 years ago
Read 2 more answers
What is the area of a rectangle whose sides are 3.2 m and 8.01 m? Answer in units of m²
alexgriva [62]

Answer:

25.632 m²

Explanation:

area = a*b

area = 3.2m * 8.01m

area = 25.632 m²

4 0
3 years ago
Read 2 more answers
What do the different colors in a line spectrum represent? why are the spectra for each element unique?
Lana71 [14]
They typically represents different wavelengths of element due to its energy emission in the form of visible light. When an electron of that particular element move from a higher energy level down to a lower energy level, it gives off energy in the form of photon emission. Atom of a certain element has a unique electron arrangement thus it can considered that particular element's spectrum is unique.
8 0
3 years ago
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