Chapter 7, Problem 19P

* Wind energy Air circulates across Earth in regular patterns. A tropical air current called the Hadley cell carries about $\text{2 }\times {\text{10}}^{\text{11}}\text{kg}$ of air per second past a cross section of Earth’s atmosphere while moving toward the equator. The average air speed is about 1.5 m/s. (a) What is the kinetic energy of the air that passes the cross section each second? (b) About $\text{1 }\times {\text{ 10}}^{\text{20}}\text{J}$ of energy was consumed in the United States in 2005. What is the ratio of the kinetic energy of the air that passes toward the equator each second and the energy consumed in the United States each second?