A Proton,which Moves Perpendicular to a Magnetic Field of 1

Multiple Choice

A proton,which moves perpendicular to a magnetic field of 1.4 T in a circular path of radius 0.074 m,has what speed? (q_p = 1.60 × 10−¹⁹ C and m_p = 1.67 × 10−²⁷ kg)

A) 7.3E+5 m/s
B) 2.8E+7 m/s
C) 5.1E+6 m/s
D) 9.9E+6 m/s
E) 3.9E+6 m/s