Lorentz mass equation

lorentz.py

import math
speedoflight = 3e8
print "lets work out the mass of something moving at a speed near the speed of light (C)"
print "what is the initial mass of your object in kg?" 
initmass = float(raw_input())
print "what is the velocity of your object in m/s?\n(note: C is 3e8, your input can have up to 17 digits before rounding.)"
velocity = float(raw_input())
if velocity == 3e8:
    print "Watch out, you are trying to divide by zero! Try again."
else:
    finalmass = initmass / math.sqrt( 1.00 - math.pow(velocity, 2) / math.pow(speedoflight, 2))
    print "the mass of your object is %rkg" % (finalmass)