Ahouse is built with a concrete slab and a big south facing window. at 100m2 and 0.1m thick, the slab has a volume of 10m3 and thus a mass of 24,000 kg. at 6: 00 am, the temperature of the slab is 16°c. the sun shines in through the window and by 2: 00 pm the slab temperature is 30°c. concrete has a specific heat of 960 j/kg k. we know that one joule (j) is equal to 1 watt-second (w sec). we also know that there are 3600 second in an hour. how much heat was added to the slab? give the answer in kwh of heat added.