A metal target sphere of 30 cm diameter suspended out in space is given a charge of +1.00 nC. Through what voltage must a distant proton be accelerated from rest (by some sort of space weapon) if it is to arrive at the sphere at a speed of 8.2*10^4 m/s? (Neglect any gravitational effects.) V= (k0*Q)/R W= qe*delta V VB-VA= k0*Q(1/rb-1/ra) I calculated the voltage for the sphere: V= (8.99*10^9)(1.00*10^-9C)/0.15m= 59.93V Then I calculated W: (1.6*10^-19)(59.93V)= 9.5888E-18J Now, this is where I'm having trouble. What is the next step? What does speed have to do with any of this? I am completely lost so any help would be greatly appreciated.