6) A 2.0 kg particle is moving such that its position vector (r) relative to the origin is r =(-2.0*t**2 i + 3.0 j) m. What is the torque (about the origin) acting on the particle at t=2.0 s?
   A1  24 k   N.m
   A2 -36 k   N.m
   A3 -24 k   N.m
   A4 -48 k   N.m
   A5   0