Variable-mass system the momentum of the system varies for Therefore, by Newton's second law Noting that u - v is the velocity of d"m" relative to "m", symbolized as v, this final equation can be arranged as In a system where mass is being ejected or ablated from a main body, the derivation is slightly different. At time "t", let a mass "m" travel at a velocity v, meaning the initial momentum of the system is Since the main body will be losing mass, d"m" will be negative, meaning that at a time "t" + d"t" the momentum of the system becomes
The Nature and Origins of Mass Opinion poorly informed, psychologically driven, and "mass-mediated" public opinion may be, it is capable of recognizing and focusing on its own conception of what matters. The Nature and Origins of Mass Opinion The Nature and Origins of Mass Opinion is a 1992 non-fiction book by political scientist John Zaller that examines the processes by which individuals form and express political opinions and the implications this has for public opinion research. The book has been called "the single most important book on public opinion since V. O. Key's 1961 classic, "Public Opinion and American Democracy"." Zaller argues that public opinion is heavily