posted by Huy Nguyen .
An aluminum wire with mass/unit length of p = 5*10^-4 kg/m lies on the ground, running east-west. The wire feels the earth's magnetic field, which has magnitude B = 5*10^-5 T. Assume the wire is in Columbia, where the Earth's magnetic field runs due north, parallel to ground. A current flows in the wire, in the west-to-east direction as shown. How large would the current have to be to lift the cable off the ground? Recall, g=9.8 m/s^2.