Question

An object is tracked by a radar station and found to have a position vector by r=(3500-160t)i + 2700j + 300k, with r in m and t in sec. The radar station's x-axis points east, its y-axis north and its z-axis vertically up. If the object is a 250-kg missile warhead, what are (a) its linear momentum (b) its direction of motion (c) its net force on it.