Mechanical energy mechanical energy of the colliding objects has been converted into an equal amount of heat. Thus, the total energy of the system remains unchanged though the mechanical energy of the system has reduced. A satellite of mass formula_4 at a distance formula_5 from the centre of Earth possesses both kinetic energy, formula_6, (by virtue of its motion) and gravitational potential energy, formula_7, (by virtue of its position within the Earth’s gravitational field; Earth's mass is formula_8). Hence, mechanical energy formula_9 of a satellite is given by If the satellite is in circular orbit, the energy conservation equation can be further
Feathers: The Evolution of a Natural Miracle Feathers: The Evolution of a Natural Miracle Feathers: The Evolution of a Natural Miracle is a 2011 natural history book by American conservation biologist Thor Hanson. Published by Basic Books and written for general audiences, the book discusses the significance of feathers, their evolution, and their history both in nature and in use by humans. "Feathers" is divided into five parts. In "Evolution", Hanson discusses the scientific debate over how feathers evolved, interviewing ornithologists Richard Prum and Alan Feduccia, as well as paleontologist Xing Xu. In "Fluff", Hanson discusses how feathers play a role in regulating a bird's body temperature