Only two forces acts on the traffic light: the tension T of the cable (upward) and the weight of the traffic light (downward). The weight is [tex]mg=(19 kg)(9.81 m/s^2)=186.39 N[/tex] If the traffic light is at equilibrium, the resultant of the two forces must be equal to zero (Netwon's second law): [tex]T-mg=0[/tex] Therefore the tension of the cable is [tex]T=mg=186.39 N[/tex]
