Relativistic Ledgers

Opposite Momenta Can Cancel

A pair can have zero total momentum while retaining positive total energy. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Opposite momenta can cancel

The left momentum 15 and right momentum minus 15 add to 0.

15+(−15)=015+(- 15)=0
Opposite momentum ledgerOpposite momenta cancel while energies add.left momentumright momentumtotal momentumtotal energy

Energy still adds

Each object carries 125 J, so total energy is 250 J.

125+125=250125+125=250
Opposite momentum ledgerOpposite momenta cancel while energies add.left momentumright momentumtotal momentumtotal energy