In proton-beam therapy, a high-energy beam of protons is 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 0.12J of proton energy in the tumor. To create the proton beam, protons are accelerated from rest through a 9000kV potential difference.
What is the total charge of the protons that must be fired at the tumor?