Assume you need 1.1 * 10^9 J per day to heat a home. Further assume, the home has a concrete floor, a footprint of 120 m2, and uses passive solar heating. If the concrete floor heats to 38C during the day and cools to 15C during the night, what thickness of concrete is requires to satisfy all the energy need for heating. You will need the specific heat of concrete, 653 J/(kgK), and the density of concrete, 2.3 tons/m3.