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Quark Model of the Neutron According to the quark model of fundamental particles, neutrons—the neutral particles in an atom’s nucleus—are composed of three quarks. Two of these quarks are “down” quarks, each with a charge of −e/3; the third quark is an “up” quark, with a charge of +2e/3. This gives the neutron a net charge of zero. What is the electric potential energy of these three quarks, assuming they are equidistant from one another, with a separation distance of 1.3 × 10-15 m? (Quarks are discussed in Chapter 32.)
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