In control theory, assuming that a system is LTI, the Laplace transform of a form of this quantity yields the transfer function. The convolution of a function f of x with a function named for this quantity of x minus y yields f of y; that is this function’s “sifting property.” For a linear differential operator L, the Green’s function of L is defined as the “response” form of this quantity. In Tsiolkovsky’s rocket equation, multiplying this quantity with (*) gravity gives the effective exhaust velocity. The Dirac delta function, whose value is zero everywhere except at the origin, (-5[1])is alternatively known as the “unit function” of this quantity. Assuming a general force F of t, this quantity equals the definite integral of “F of t times d t.” For 10 points, name this quantity defined as the change of momentum. ■END■ (10[2])