
#1
Dec813, 10:31 AM

P: 17

Hi, apparently you can calculate the amount of energy the sun delivers to each square meter of the earth using an umbrella, tin can, water and a thermometer. You put the tin can outside with some water in it and put the umbrella over it until it reaches ambient temperature. You then take the umbrella off and measure how quickly the temperature of the water increases in the can. From this you should get a value of roughly 1000 watts/square meter if you take the measurements at midday day near the equator where the sun is roughly at 90 degrees. Could someone explain exactly how this works as I saw it on a program which didn't explain how you actually calculate it. What measurements of the water do you take and what maths do you do to arrive at 1000Watts/square meter? Thank you for any help offered




#2
Dec813, 11:18 AM

P: 1,229

It's just the heat capacity formula
Q=cmΔT Where Q is the heat absorbed by the water, m is its mass, c is it's heat capacity and ΔT the change in temperature. The power is than calculated by dividing the energy by the amount of n time it took to absorb it P = Q/Δt where Δt is the elapsed time. 


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