The sun transfers energy to the earth by radiation at a rate of approximately 1.00kW per square meter of surface. If this energy could be collected and converted to electrical energy with 25% efficiency how large an area (in square kilometers) would be required to collect the electrical energy used by the United States? (1.0X10^19 joules per year). If the solar collectors were arranged in a square array, what would be the length of its sides in kilometers and in miles?