A heavy nucleus N, at rest, undergoes fission $$N \rightarrow P + Q$$, where P and Q are two lighter nuclei. Let $$\delta = M_N − M_P − M_Q$$, where $$M_P$$, $$M_Q$$ and $$M_N$$ are the masses of P, Q and N, respectively. EP and EQ are the kinetic energies of P and Q, respectively. The speeds of P and Q are $$v_P$$ and $$v_Q$$, respectively. If c is the speed of light, which of the following statement(s) is(are) correct?