v Your answer is correct. (d) Now consider a specific case: a proton and an antiproton, each with an initial speed of 7.0 x 107 m/s when they are far apart. When these two particles collide, they react to form two new particles: a positive pion (z+, charge + ) and a negative pion (7, charge e). Each pion has a rest mass of 2.5 10728 kg. These pions have enough energy that they move away from each other. When these two pions have moved very far away from each other, how fast is each pion going, v? v = | 2.96804e+8 m/s Attempts: 1 of 4 used Part 5 v Your answer is correct. (e) When the pions are far apart, what is true of their speed? _ Part 6 X Your answer is incorrect. (f) As the pions move away from each other, the ratio of the absolute value of electric potential U energy to the final total kinetic energy K of the two pions ( K ) changes. At some point, the potential energy becomes negligible compared to the final total kinetic energy K. We can consider that the value of the ratio (':; is about 0.01 when U