In proton-beam therapy, a high-energy beam of protons are fired at a tumor. As the protons stop in the tumor their kinetic energy breaks apart the tumor's DNA, thus killing the tumor cells. For one patient, it is desired to deposit 0.12 Joule of proton energy in the tumor. To create the proton beam, protons are accelerated from rest through a 9000 kV potential difference.
Find the total charge of protons that must be fired at tumor?