At What Speed Would a Proton Need to Circle the Earth

Short Answer

At what speed would a proton need to circle the Earth at a height of 1 000 km above the equator if the Earth's magnetic field is horizontal and directed north-south,with an intensity of 4.00 *10 ^{- 8} T? (The radius of the Earth is 6 400 km and the charge and mass of the proton are q = 1.60 *10 ^{- 19} C and m_p = 1.67 * 10 ^{- 27} kg.Ignore relativistic corrections. )