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Anastasy [175]
3 years ago
14

Compute the atomic density (the number of atoms per cm3 rather than mass density g/cm3) for a perfect crystal of silicon at room

temperature, given that the room temperature density and atomic weight of silicon are 2.33 g/cm3 and 28.09 g/mol, respectively.
Hint: you do NOT need any information about the crystal structure of silicon to solve for this quantity, based on the information provided in this particular problem.
Be sure to use values exactly as given and do not round until the final answer.
Use 6.022x1023 , exactly, for Avogadro's Number.
Answer Format: XEX where EX stands for *10x
Units: atoms/cm3
Example: So for an answer of 158123.126 you would type: 2E5 since only a whole number is prescribed for the prefix.
Engineering
1 answer:
Ann [662]3 years ago
5 0

Answer:

5E22 atoms/cm³

Explanation:

We need to find the number of moles of silicon per cm³

number of moles per cm³ = density/atomic weight = 2.33 g/cm ÷ 28.09 g/mol = 0.083 mol/cm³.

Since there are 6.022 × 10²³ atoms/mol, then the number of atoms of silicon per cm³ = number of atoms per mol × number of moles per cm³

= 6.022 × 10²³ atoms/mol × 0.083 mol/cm³

= 0.4995 × 10²³ atoms/cm³

= 4.995 × 10²² atoms/cm³

≅ 5 × 10²² atoms/cm³

= 5E22 atoms/cm³

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Alcohol consumption tends to cause more ___________ behavior.
lions [1.4K]

Answer:

Aggressive behavior

Explanation:

Alcohol consumption tends to cause more Aggressive behavior.

The consumption of alcohol plays a more role in our culture but drinking of too much alcohol can cause drowsiness, vomiting, Upset stomach, slurred speech, heart damage, infertile, numbness lung infections, and many more. Also too much alcohol can cause violence, anger and so on in the society.    

8 0
3 years ago
What is the instantaneous center of zero velocity? List two approaches for determining the is the instantaneous center of zero v
Lera25 [3.4K]

Explanation:

Instantaneous center:

   It is the center about a body moves in planer motion.The velocity of Instantaneous center is zero and Instantaneous center can be lie out side or inside the body.About this center every particle of a body rotates.

From the diagram

Where these two lines will cut then it will the I-Center.Point A and B is moving perpendicular to the point I.

If we take three link link1,link2 and link3 then I center of these three link will be in one straight line It means that they will be co-linear.

I_{12},I_{23},I_{31} all\ are\ co-linear.

5 0
3 years ago
Which type of engineering design uses an already-existing design?
Arte-miy333 [17]
The answer is D I’m 90% sure
4 0
3 years ago
Read 2 more answers
A cylinder of aluminum-magnesium alloy 0.5 m long is subjected to an elastic tensile stress of 10.2 MPa. The measured elastic el
elena55 [62]

Answer:

E= 15 GPa.

Explanation:

Given that

Length ,L = 0.5 m

Tensile stress ,σ = 10.2 MPa

Elongation ,ΔL = 0.34 mm

lets take young modulus  = E

We know that strain ε given as

\varepsilon =\dfrac{\Delta L}{L}

\varepsilon =\dfrac{0.34}{0.5\times 1000}

\varepsilon =0.00068

We know that

\sigma = \varepsilon  E\\\\E=\dfrac{10.2}{0.00068}\\E= 15000\ MPa\\E=15\ GPa

Therefore the young's modulus will be 15 GPa.

8 0
3 years ago
A thick steel slab (rho= 7800 kg/m3 , cp= 480 J/kg K, k= 50 W/m K) is initially at 300 °C and is cooled by water jets impinging
dimaraw [331]

Answer:

t = 2244.3 sec

Explanation:

calculate the thermal diffusivity

\alpha = \frac{k}{\rho c}

           = \frac{50}{7800\times 480} = 1.34 \times 10^{-5} m^2/s

                   

Temperature at 28 mm distance after t time  = =  50 degree C

we know that

\frac[ T_{28} - T_s}{T_i -T_s} = erf(\frac{x}{2\sqrt{at}})

\frac{ 50 -25}{300-25} = erf [\frac{28\times 10^{-3}}{2\sqrt{1.34\times 10^{-5}\times t}}]

0.909 = erf{\frac{3.8245}{\sqrt{t}}}

from gaussian error function table , similarity variable w calculated as

erf w = 0.909

it is lie between erf w = 0.9008  and erf w = 0.11246 so by interpolation we have

w = 0.08073

erf 0.08073 = erf[\frac{3.8245}{\sqrt{t}}]

0.08073 = \frac{3.8245}{\sqrt{t}}

solving fot t we get

t = 2244.3 sec

3 0
3 years ago
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