Relativistic angular momentum can be compactly abbreviated in tensor index notation where the indices "i" and "j" take the values 1, 2, 3. On the other hand, the components can be systematically displayed fully in a 3 × 3 antisymmetric matrix This quantity is additive, and for an isolated system, the total angular momentum of a system is conserved. In classical mechanics, the three-dimensional quantity for a particle of mass "m" moving with velocity u has the dimensions of "mass moment" – length multiplied by mass. It is related to the boost (relative velocity) of the centre of mass (COM) of the particle
Bussard ramjet to accelerate into the solar wind. However, in their calculations they assumed that: In the Zubrin/Andrews interplanetary ramjet design, they calculated that the drag force d/dt("mv") equals the mass of the scooped ions collected per second multiplied by the velocity of the scooped ions within the solar system relative to the ramscoop. The velocity of the (scooped) collected ions from the solar wind was assumed to be 500,000 m/s. The exhaust velocity of the ions when expelled by the ramjet was assumed not to exceed 100,000 m/s. The thrust of the ramjet d/dt("mv") was equal to the mass of ions