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At a depth of 1030 m in Lake Baikal (a fresh water lake in Siberia), the pressure has increased by 100 atmospheres (to about 107 N/m2). By what volume has 1.0 m3 of water from the surface of the lake been compressed if it is forced down to this depth? The bulk modulus of water is 2.3 Ă— 109 Pa.

Respuesta :

Answer:

A volume of a cubic meter of water from the surface of the lake has been compressed in 0.004 cubic meters.

Explanation:

The bulk modulus is represented by the following differential equation:

[tex]K = - V\cdot \frac{dP}{dV}[/tex]

Where:

[tex]K[/tex] - Bulk module, measured in pascals.

[tex]V[/tex] - Sample volume, measured in cubic meters.

[tex]P[/tex] - Local pressure, measured in pascals.

Now, let suppose that bulk remains constant, so that differential equation can be reduced into a first-order linear non-homogeneous differential equation with separable variables:

[tex]-\frac{K \,dV}{V} = dP[/tex]

This resultant expression is solved by definite integration and algebraic handling:

[tex]-K\int\limits^{V_{f}}_{V_{o}} {\frac{dV}{V} } = \int\limits^{P_{f}}_{P_{o}}\, dP[/tex]

[tex]-K\cdot \ln \left |\frac{V_{f}}{V_{o}} \right| = P_{f} - P_{o}[/tex]

[tex]\ln \left| \frac{V_{f}}{V_{o}} \right| = \frac{P_{o}-P_{f}}{K}[/tex]

[tex]\frac{V_{f}}{V_{o}} = e^{\frac{P_{o}-P_{f}}{K} }[/tex]

The final volume is predicted by:

[tex]V_{f} = V_{o}\cdot e^{\frac{P_{o}-P_{f}}{K} }[/tex]

If [tex]V_{o} = 1\,m^{3}[/tex], [tex]P_{o} - P_{f} = -10132500\,Pa[/tex] and [tex]K = 2.3\times 10^{9}\,Pa[/tex], then:

[tex]V_{f} = (1\,m^{3}) \cdot e^{\frac{-10.1325\times 10^{6}\,Pa}{2.3 \times 10^{9}\,Pa} }[/tex]

[tex]V_{f} \approx 0.996\,m^{3}[/tex]

Change in volume due to increasure on pressure is:

[tex]\Delta V = V_{o} - V_{f}[/tex]

[tex]\Delta V = 1\,m^{3} - 0.996\,m^{3}[/tex]

[tex]\Delta V = 0.004\,m^{3}[/tex]

A volume of a cubic meter of water from the surface of the lake has been compressed in 0.004 cubic meters.