Here's my problem: A particle with charge 4.5E-19 C travels in a circular orbit with radius .465 m due to the force exerted on it by a magnetic field with magnitude 1.7 T and perpendicular to the orbit. a) What is the magnitude of the momentum p of the particle? I used the equation R=(mv)/(qB) and calculated mv (linear momentum) to be 3.6E-19 kg*m/s. b) What is the magnitude of the angular momentum L of the particle? Herein lies the rub! Angular momentum = v/R = qB/m I don't know velocity or mass independently, only their product (mv). So how do I calculate angular momentum? Thanks for any help!