The bar magnet of magnetic moment $2.0\mathrm{A}-{\mathrm{m}}^2$ is free to rotate about a vertical axis through its centre. The magnet is released from rest from the east-west position. Find the kinetic energy of the magnet as it takes the north-south position. The horizontal component of the earth’s magnetic field is $\mathrm{B}=25\mathrm{\mu T}$. Earth’s magnetic field is from south to north__________ $\mathrm{\mu J}$