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How heat accelerate brood rearing.
If we measure the brood area of 10 cm radius, 10 cm x 10 cm x pii 3,14 = 314 cm2
Then if heat add the radius to 15 cm, the area will be 15 cm x 15 cm x pii 3,14 = 707 cm2
So the brood area in one frame is 2,25 bigger.
But the whole brood area is a ball. Lets look the rise of volume of brood area.
4/3*3,14 * pii3 10x10x10 = 4 200
50% more to radius
4/3*3,14 * pii3 15x15x15 = 14 100
The bigger radius has 3,4 fold volume compared to smaller radius.
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