You will be given a definition of a task first, then some input of the task.
In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

By replacing generalized velocities with the conjugate form of this quantity, one can reformulate Lagrangian mechanics as Hamiltonian mechanics. In fluid dynamics, the Cauchy equation is equivalent to the conservation of this quantity. Its operator in quantum mechanics is equal to i h-bar times the partial derivative with respect to position. The conservation of this quantity proceeds from translational symmetry according to Noether's theorem. According to the de (*) Broglie relation, wavelength is equal to Planck's constant over this quantity. This quantity is conserved by inelastic collisions. The change in this quantity is defined as the impulse. For 10 points, name this quantity conventionally equal to mass times velocity.
Output:
Science