The power tag has no wiki summary.
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3answers
92 views
Power of a runner
How can someone calculate the power in watt that a runner produces, when he runs uphill and downhill?
Is there any algorithm? It is important to take under consideration the uphill and downhill ...
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1answer
53 views
Calculating the mechanical power of a water pump
Say I want to pump water from one container to another. The water levels are 3 meters apart, and I want to pump 10 litres per hour. I figure the mechanical power necessary, assuming no losses, is:
$$
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1
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1answer
108 views
Inefficiency Comparison of Car Air Conditioning vs. Open Windows
On a recent long, hot journey in Spain, I was pondering which was the most efficient way of cooling the car. Which of these would be the most effective?
Switching on the air conditioning, thereby ...
1
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1answer
452 views
Finding electric power generated using heat transfer
I'm working through an example I have been given to study. Suppose I have a 2m X 4m photovoltaic panel on my roof that is irradiated with a solar flux of $G_s = 700W/m^2$.
Given:
$\alpha_s = 0.83$
...
0
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1answer
64 views
How to understand the thermal radiation?
I am studying the thermal radiation (Stefan–Boltzmann law) by myself
$$P = \epsilon \sigma A T^4$$
here $\epsilon$ is the emissivity, $\sigma$ is Stefan-Boltzmann constant, $A$ is the surface area ...
0
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1answer
197 views
What is the relation between fan blade and air flow CFM?
If I have a motor use in 2 cases, the 1st case I use standard blade and 20% longer blade in the 2nd case.
People told me that longer blade will create higher CFM. However, I am not totally sure. ...
2
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0answers
284 views
How much power to keep surface of aluminum plate at given temperature?
I want to heat one side of an aluminum plate enough to hold the other side of that plate $100K$ above ambient. I'm willing to assume that the heated side of the plate is "well" insulated (along with ...
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0answers
93 views
Energy efficiency Vs power efficiency
I want to understand if there can be any real difference between the requirement of Energy efficiency and the requirement of power efficiency for a physical system. For example for CMOS-based digital ...
