Many decisions are made on the basis of the payback period: the time it will take through savings to equal the capital cost of an investment. Acceptable payback times depend upon the business or philosophy one has. (For some industries, a payback period is as small as two years.) Suppose you wish to install the extra insulation in Exercise. If energy cost $1.00 per million joules and the insulation was $4.00 per square meter, then calculate the simple payback time. Take the average ΔT for the 120 day heating season to be 15.0ºC.

Many decisions are made on the basis of the payback period: the time it will take through savings to equal the capital cost of an investment. Acceptable payback times depend upon the business or philosophy one has. (For some industries, a payback period is as small as two years.) Suppose you wish to install the extra insulation in Exercise. If energy cost $1.00 per million joules and the insulation was $4.00 per square meter, then calculate the simple payback time. Take the average ΔT for the 120 day heating season to be 15.0ºC.

Physics for Scientists and Engineers: Foundations and Connections

1st Edition

ISBN:9781133939146

Author:Katz, Debora M.

Publisher:Katz, Debora M.

Chapter1: Getting Started

Section: Chapter Questions

Problem 48PQ: In 2011, artist Hans-Peter Feldmann covered the walls of a gallery at the New York Guggenheim Museum...

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Many decisions are made on the basis of the payback period: the time it will take through savings to equal the capital cost of an investment. Acceptable payback times depend upon the business or philosophy one has. (For some industries, a payback period is as small as two years.) Suppose you wish to install the extra insulation. If energy cost $1.00 per million joules and the insulation was $4.00 per square meter, then calculate the simple payback time. Take the average for the 120 day heating season to be 15.0C.
How much efficiency would a solar panel of surface area A = 2 m² need to have to generate 1.4 kWh of electricity in a region where the solar power density is 4.5 kWh/m2/day? Write the efficiency in decimal value rounded off to 2 decimal places, not as a percentage. For instance you would write 0.25 and not 25%.
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The total consumption of electrical energy in the United States is about 1.0 1019 joules per year. What is the average rate of electrical energy consumption in watts? If the population of the United States is 300 million, what is the average rate of electrical energy consumption per person? The sun transfers energy to the earth by radiation at a rate of approximately 1.0 kW per square meter of surface. If this energy could be collected and converted to electrical energy with 40 % efficiency, how great an area (in square kilometers) would be required to collect the electrical energy used by the United States?
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