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## Homework Statement

At Earth’s location, the intensity of sunlight is 1.5 kW/m^2. If no energy escapes

Earth, by how much would Earth’s mass increase in a day? (Radius of Earth is

6.37 × 10^6 m.)

## The Attempt at a Solution

ok so, at any one time, half of the earth is lit.

so surface area lit = 1/2 x 4[tex]\Pi[/tex]r

^{2}=

2.55x10

^{14}m

^{2}

intensity = 1500 W/m

^{2}

so energy per second on earth = 1500 x 2.55x10

^{14}= 3.82 x 10

^{17}J

energy per day = 3.82 x 10

^{17}x 60 x 60 x 24 = 3.3 x 10

^{22}

so E = mc

^{2}

so m = E / c

^{2}= 3.67 x 10

^{5}kg

but the correct answer is half of this. so where did i go wrong? thanks for help!