July 13, 2007
How many joules of solar energy fall on your back as you work on your tan for 0.70h?
Posted by: admin : Category: Uncategorized
ginger_jj asked:
The intensity of electromagnetic waves from the sun is 1.4 kW/m^2 just above the earth’s atmosphere. Eighty percent of this reaches the surface at noon on a clear summer day.
Suppose you model your back as a 27cm & 51cm rectangle.
How many joules of solar energy fall on your back as you work on your tan for 0.70h?
The intensity of electromagnetic waves from the sun is 1.4 kW/m^2 just above the earth’s atmosphere. Eighty percent of this reaches the surface at noon on a clear summer day.
Suppose you model your back as a 27cm & 51cm rectangle.
How many joules of solar energy fall on your back as you work on your tan for 0.70h?
July 13th, 2007 at 11:20 pm
80% of 1.4 = 1.12 kW / m²
Area = 0.27 * 0.51 = 0.138 m²
Power = 1.12 * 0.138 = 0.154 kW
Energy = Power * Time
Time = 0.7 * 3600 = 2520 seconds
Energy = 0.154 * 2520 = 389 Joules