Restoring the classical momentum label chapter six turns off shows the relativistic correction growing with both speed and mass. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Chapter three's own example is this scan's first row

Chapter three cited this exact case once: mass 4 kg at the slower speed gives classical momentum 12 kg m/s against the checked relativistic momentum 15 kg m/s, a gap of 3.

1512=315\,-\,12=3
Momentum gap rowThe momentum and classical-momentum values feed a checked gap.momentum=15 kg*m/sclassical=12 kg*m/sgap=3 kg*m/s

Neither chapter five nor six ever displayed this gap again

Chapter five's mass scan and chapter six's energy-triangle scan both compute the same momenta at these masses, but chapter six explicitly turns the classical label off. Restoring it across three rows shows the gap growing with both speed and mass.

γmpclassicalprelgap5441215353312208536244016\begin{array}{c|c|c|c|c}\gamma&m&p_{\text{classical}}&p_{\text{rel}}&\text{gap}\\\frac{5}{4}&4&12&15&3\\\frac{5}{3}&3&12&20&8\\\frac{5}{3}&6&24&40&16\\\end{array}
Momentum gap rowThe momentum and classical-momentum values feed a checked gap.momentum=20 kg*m/sclassical=12 kg*m/sgap=8 kg*m/s

Doubling mass at the same speed doubles the gap too

The third row keeps the faster gamma and doubles mass to 6 kg. Classical momentum doubles to 24 kg m/s, relativistic momentum doubles to 40 kg m/s, and the gap doubles too, to 16.

4024=1640\,-\,24=16
Momentum gap rowThe momentum and classical-momentum values feed a checked gap.momentum=40 kg*m/sclassical=24 kg*m/sgap=16 kg*m/s