momentumiin

Momentumiin is the illative case form of the Finnish noun momentumi, meaning momentum. In Finnish grammar, the illative case (ending -iin) indicates direction toward or into something, or into a particular state. Therefore momentumiin is used in sentences where one refers to moving toward momentum or entering a state characterized by momentum. The term momentumi itself is a loanword from Latin momentum and is used in physics to denote the quantity of motion.

In physics, linear momentum, or momentumi, is defined for a body as p = m v, a vector quantity with units of kilogram meter per second (kg·m/s). It depends on mass and velocity and is conserved in isolated systems according to the conservation of momentum. Impulse equals the change in momentum (F Δt = Δp). For rotation, angular momentum L = r × p is analogous and also conserved in the absence of external torques. In relativity, momentum is p = γ m v, where γ is the Lorentz factor, and momentum couples to energy via the energy-momentum relation E^2 = (pc)^2 + (m c^2)^2.