Question #42460

This question tests the application of the Impulse-Momentum Theorem and Galilean velocity addition across changing reference frames in successive decays.

The primary trap is the 'Single-Event Conservation' fallacy, where students incorrectly lump the sequential decays into a single simultaneous 3-body decay ($A \rightarrow C + D + E$) with total energy $5Q$.

This flawed assumption allows momentum to be shared arbitrarily among all three particles, yielding an artificially high maximum kinetic energy ($\frac{5}{2}Q$) for particle $D$ by assuming $C$ and $E$ recoil together.

By enforcing the intermediate state (nucleus $B$), the physical constraints of the sequential momentum impulses are respected, demonstrating that steady-state energy conservation cannot bypass the time-dependent momentum distribution of intermediate frames.