Force F = (1.23 N )i - (2.01 N k acts on a pebble with position vector 7' = (6.42 m )j - (7.23 m )k, relative to the origin. What is the resulting torque acting on the pebble about (a) the origin and (b) a point with coordinates (5.62 m, 0, -8.51 m)? (a) Number i i k Units (b) Number i k Units + +