Use the definition of the derivative to find an expression for the instantaneous velocity of an object moving with rectilinear motion according to the given function relating s (in ft) and t (in s). Then calculate the instantaneous velocity for the given value of t. s = 8t + 16; t = 1 . . . The expression for the instantaneous velocity of the object is (Simplify your answer.) The instantaneous velocity after 1 s is ft / s