A horizontal uniform bar of mass 2.7 kg and length 3.0 m is hung horizontally on two vertical strings. String 1 is attached to the end of the bar, and string 2 is attached a distance 0.7 m from the other end. A monkey of mass 1.35 kg walks from one end of the bar to the other. Find the tension T_1 in string 1 at the moment that the monkey is halfway between the ends of the bar.