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The intensity of electromagnetic waves from the sun is 1.4 kW/m2 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 25 cm * 52 cm rectangle.How many joules of solar energy fall on your back as you work on your tan for 0.90 h? Answer in Joules.

Answer :

Olajidey

Answer:

4.7 × 10⁵J

Explanation:

E = I * a * t

80% = 0.80

25cm = 0.25m

52cm = 0.52m

0.90h = 3240s

E = (0.80)(1400)(0.25 * 0.52)(3240)

= 4.7 * 10⁵J

onyebuchinnaji

The solar energy that falls on your back as you work is 471,744 J.

The given parameters;

  • intensity of the wave, I = 1.4 kW/m²
  • dimension of your back, = 25 cm by 52 cm
  • duration, t = 0.9 h = 0.9 x 3600 s = 3240 s
  • percent of incident ray on you, = 80%

The area of your back is calculated as;

[tex]A = 0.25 \times 0.52\\\\A = 0.13 \ m^2[/tex]

The power of the incident rays;

[tex]P = I A\\\\P = 1,400 \times 0.13\\\\P =182 \ W[/tex]

The total energy of incident ray is calculated as;

[tex]E = Pt\\\\E = 182 \times 3240\\\\E = 589,680 \ J[/tex]

The solar energy that falls on your back is;

[tex]E = 0.8 \times 589,680\\\\E = 471,744 \ J[/tex]

Thus, the solar energy that falls on your back as you work is 471,744 J.

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