Mass in special relativity what causes these particles to be termed "massless." However, even massless particles have a relativistic mass, which varies with their observed energy in various frames of reference, The invariant mass is the ratio of four-momentum (the four-dimensional generalization of classical momentum) to four-velocity: and is also the ratio of four-acceleration to four-force when the rest mass is constant. The four-dimensional form of Newton's second law is: The relativistic expressions for "E" and "p" obey the relativistic energy–momentum relation: where the m is the rest mass, or the invariant mass for systems, and "E" is the total energy. The equation is
Mercy Multiplied three financial principles for the program: According to the three guiding principles that founder Nancy Alcorn established, the Mercy Multiplied website states that they do not accept government funding, and as such, are supported solely by donations from individuals, organizations and other ministries. With regard to fund raising events, Mercy Multiplied host gala dinners, Christmas donation drives and running marathons throughout the year, and invite visitors to their website to donate by becoming a financial partner or "sponsoring" a girl. Mercy Multiplied also sell resources to raise funds such as books and sermons by founder Nancy Alcorn, as well as