Which situation would result in a decrease of 39.2 J in the described object's gravitational potential energy?

An architect plans to use solar energy to heat the next house he designs. what principle of absorption and infrared energy can be applied to the design of the new house? how could she apply to those principals?

The three classes of rocks are sedimentary, metamorphic, and igneous. how are rocks classified into one of these three groups?

The radioactive isotope of lead, pb-209, decays at a rate proportional to the amount present at time t and has a half-life of 3.3 hours. if 1 gram of this isotope is present initially, how long will it take for 80% of the lead to decay? (round your answer to two decimal places.)