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Suppose the dam is 80% efficient at converting the water's potential energy to electrical energy. How many kilograms of water must pass through the turbines each second to generate 45.0 MWMW of electricity? This is a typical value for a small hydroelectric dam.

Respuesta :

Answer:

[tex]\dot m = 163877.114\,\frac{kg}{s}[/tex]

Explanation:

Let assume that the water dam has a fall of 35 meters. The required instantaneous potential energy is:

[tex]\dot E_{g} = \frac{\dot E_{el}}{\mu_{el}}[/tex]

[tex]\dot E_{g}= \frac{45\times 10^{6}\,W}{0.8}[/tex]

[tex]\dot E_{g} = 56.25\cdot 10^{6}\,W[/tex]

The instantaneous potential energy has the following model:

[tex]\dot E_{g} = \dot m \cdot g \cdot \Delta h[/tex]

The mass flow rate needed to produced the required energy production:

[tex]\dot m = \frac{56.25\times 10^{6}\,W}{(9.807\,\frac{m}{s^{2}} )\cdot (35\,m)}[/tex]

[tex]\dot m = 163877.114\,\frac{kg}{s}[/tex]

This question involves the concepts of efficiency, potential energy, and electrical energy.

"2.2 x 10⁵ kg/s" of water must pass through the turbines each second, assuming a waterfall height of 26 m.

First, we will use the formula for the efficiency of conversion from potential energy to electrical energy.

[tex]Efficiency=\frac{electrical\ power}{potential\ energy/t}\\\\\frac{potential\ energy}{t} = \frac{electrical\ energy}{efficiency}\\\\\frac{mgh}{t}=\frac{45\ MW}{0.8}\\\\\frac{mgh}{t}=56.28\ MW=56.28\ x\ 10^6\ W[/tex]

assuming h = 26 m:

[tex]\frac{m}{t}=\frac{56.28\ x\ 10^6\ W}{(9.81\ m/s^2)(26\ m)}\\\\\frac{m}{t}=2.2\ x\ 10^5\ kg/s[/tex]

Learn more about efficiency here:

https://brainly.com/question/3877244?referrer=searchResults

The attached picture shows the pyramid representing energy efficiency.

Ver imagen hamzaahmeds