1. The problem statement, all variables and given/known data An unknown hydrocarbon ion required 9.415*10^-6 seconds to travel through the 0.250 T magnetic field of a mass spectrometer with a radius of curvature of 14.1 cm. Since the magnetic chamber is shaped like a 'D' it only travels half way around the circle. a. find the speed of the ion through the magnetic field b. identity of the ion using the charge to mass ratio (q/m) 2. Relevant equations Fm = qvB Fm=Fnet=Fc qvB=mv^2/r Fc=(4π^2/T^2) Unknown variables: q (charge), m (mass), v (velocity) or V (voltage) 3. The attempt at a solution a. Rearranging the formula gives me v=qBr/m. I do not have the (q/m) ratio, so that creates two unknown variables. Next, I tried substituting (4π^2/T^2) as an equivalent for qvB. The Fm is 4.453680806*10^11 N. After this step I am stuck. ANSWER FROM THE BOOK: The velocity is 4.7*10^4 m/s, and the substance is pentane, with a (q/m) ratio of 1.34*10^6.