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| ### Statement |
| ### Statement |
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| $5.4.17.$ [Insert problem description here] |
| $5.4.16*.$ [Insert problem description here] |
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| __Example Statement__: |
| __Example Statement__: |
| $1.1.1.$ Determine the coordinate $x(t)$ of a body as a function of time $t$, given that its acceleration is defined as $a(t) = bt$, where $b$ is a constant. |
| $1.1.1.$ Between two flat parallel plates located at a distance δ from each other, there |
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| is a monatomic gas (the free path of atoms is much longer than δ). Estimate |
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| the heat flux density if the temperature of the plates is maintained at T and |
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| T + ∆T, respectively, and the unit volume of gas contains n' atoms; µ is the |
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| mass of the atom |
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| ### Solution |
| ### Solution |
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| [Your solution should be placed here] |
| [Your solution should be placed here] |
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| __Example Solution__: |
| __Example Solution__: |
| The acceleration of the body defined by |
| Heat flow is defined by |
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| $$a(t) = bt$$ |
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| $$J =\frac{ΔE}{A*t} $$ |
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| We know that acceleration is the time derivative of velocity: |
| We know that the change of the energy is given by |
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| $$a(t) = \frac{d v(t)}{d t}$$ |
| $$ΔE = \frac{nRΔT}{\gamma-1}$$ |
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| To find the velocity $v(t)$, we integrate $a(t)$ with respect to time: |
| Where (n) is the number of moles |
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| $$v(t) = \int a(t) \, dt = \int b t \, dt$$ |
| We know that Heat flow then |
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| If the initial velocity is $v(0) = 0$, then the velocity becomes: |
| $$J = \frac{nRΔT}{(\gamma-1)A*t}$$ |
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| $$v(t) = \frac{b t^2}{2}$$ |
| We know that the time is given by because (the free path of atoms is much longer than δ) furthermore λ>>δ therefore the average collision between the molecules will be δ: |
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| Likewise, integrate $v(t)$ with respect to time: |
| $$t = \frac{δ}{v}$$ |
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| $$x(t)= \int v(t) \, dt = \frac{b}{2} \int t^2 \, dt$$ |
| Likewise: |
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| From where the coordinate from time, considering the initial conditions: |
| $$J = \frac{nRΔTv}{(\gamma-1)A*δ}$$ |
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| $$\boxed{x(t)=\frac{bt^3}{6}}$$ |
| Now we have to: |
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| $$A*δ=V$$ |
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| So from the previous equations we have to: |
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| $$J = \frac{nRΔTv}{(\gamma-1)V}$$ |
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| Another way to write this equation is: |
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| $$J = \frac{n'KΔTv}{(\gamma-1)}$$ |
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| Where (n') is the number of the atoms |
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| $$v=\ |
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| #### Answer |
| #### Answer |
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