Avacuum chamber in the basement of kettering university is filled with a uniform magnetic field of magnitude 6.8×10−2t pointing in the negative y -direction. choose your coordinate system so that the origin coincides with the floor of the chamber and the positive z -direction points vertically upward. laying on the floor of the chamber are two cylindrical iron rods (one long and one short) laying parallel to the x -axis. the long iron rod has a length of 1.63m and a radius of 2×10−3m , while the short iron rod has a length of 5×10−2m and a radius of 2×10−3m . the centers of the two rods are separated by a distance of 6.9×10−2m . the resistivity of iron is 9.7×10−8ωm . at t= 0s , a student connects the ends of the long rod to the terminals of a 130v battery with extremely thin and light wires so that a conventional current flows through the rod in the positive x -direction.

the long rod remains connected to the first battery, and at t=13s another student connects the ends of the short rod to the terminals of a 220vbattery so that a conventional current flows through it in the positive x -direction.

what is the magnitude of the net magnetic force exerted on the short rod immediately after connecting it to the second battery?