The force exerted by a string, rope, tape, or other flexible object. At every point in the flexible object, an elementary section of it feels thesame force in each direction along the flexible body, and at the ends this same force is directed toward the flexible body.
A rope run about a frictionless pulley can change the direction of the force of tension at the ends, since the direction of the rope defines the direction along which this force acts. (You can change the direction by running a rope around an object with friction, as well, but in that case you mjus consider the frictional forces as well).In the case of at Atwood's Machine, the rope runs over a frictionless pulley and changes the direction of the force, since both ends of the rop exert and upward force on the masses (See ______ )