An electron travels in a circle of radius 6.1 m while under the influence of an unknown magnetic field, directed perpendicular to its velocity. If the particle makes 6.6 trillion complete revolutions per second, determine the magnitude of the magnetic field, in Tesla.
F = d/dt(mv) = m a if m is constant rest mass
a = v^2/r
omega = angular velocity
= 2 pi rad/rev *6.6*10^18 rev/s
= 4.15 * 10^19 rad/s
v = omega * r = 4.15 * 10^19 *6.1 = 25.3 *10^19 meters/second
this is many times the speed of light which is about 3*10^8 m/s
You could try using the relativistic mass but you will discover that it is imaginary;
It is very hard to go many times the speed of light unless you are in a science fiction movie.