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 feathered flight has influenced human aviation. Hanson describes the behavior of birds-of-paradise and the role of their elaborate feathers in sexual selection. Hanson also visits the Las Vegas Strip and observes how feathers play a role in pageant shows like "Jubilee!". Hanson interviews Marios Ignadiou, the head of "Jubilee!"'s costume shop, as well as fashion designer Pete Menefree. Hanson then describes the history of the feather trade in fashion. In the period before World War I, feathers were highly valuable commodities. Wanting to capitalize on the economic strength of feathers, the government of South Africa sponsored the Trans-Saharan Ostrich Expedition,