I could really use some help on this one:
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 0.12 of proton energy in the tumor. To create the proton beam, protons are accelerated from rest through a 9000 potential difference.

Question

I could really use some help on this one:  
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 0.12 of proton energy in the tumor. To create the proton beam, protons are accelerated from rest through a 9000 potential difference.

tanner23456 · Answer

What is the total charge of the protons that must be fired at the tumor?

anonymous · Answer

One proton with one charge deposits .12 of its energy in the tumor.  It has 9000 units of energy.  so each proton with one charge is to deposit 1080 units of energy.  You do not have the total energy required for the treatment or the total volume of the tumor.    You can't find net energy to be deposited in the tumor therefore you cannot determine the total charge