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 vultures and their feathers, and later that day, as he went on a run, he noticed four turkey vultures keeping watch over a roadkill deer. One of the vultures began flapping and dropped a feather at Hanson's feet. Moved by this coincidence, Hanson decided then to write a book about feathers. Basic Books first published "Feathers" in hardcover in 2011. In 2012, Basic Books published it in paperback as well, and the book has also been published as an ebook and audiobook. An essay-length adaptation titled "The Multiple Miracles of Bird Feathers" appeared in the January–February 2012 edition of "Audubon",