  We introduce various quantitative and mathematical definitions for price
momentum of financial instruments. The price momentum is quantified with
velocity and mass concepts originated from the momentum in physics. By using
the physical momentum of price as a selection criterion, the weekly contrarian
strategies are implemented in South Korea KOSPI 200 and US S&P 500 universes.
The alternative strategies constructed by the physical momentum achieve the
better expected returns and reward-risk measures than those of the traditional
contrarian strategy in weekly scale. The portfolio performance is not
understood by the Fama-French three-factor model.
