  We use the logistic equation to model the dynamics of the GDP and the trade
of the six countries with the highest GDP in the world, namely, USA, China,
Japan, Germany, UK and India. From the modelling of the economic data, which
are made available by the World Bank, we predict the maximum values of the
growth of GDP and trade, as well as the duration over which exponential growth
can be sustained. We set up the correlated growth of GDP and trade as the phase
solutions of an autonomous second-order dynamical system. GDP and trade are
related to each other by a power law, whose exponent seems to differentiate the
six national economies into two types. Under conducive conditions for economic
growth, our conclusions have general validity.

Physics and Society;General Economics;Economics