Explain how spending on human capital, physical capital and technology development feeds economic growth

Physical capital raises output per worker through capital deepening, and in the neoclassical model its effect on growth fades as diminishing returns set in. Some capital, such as information and communication technology and public infrastructure, generates spillovers that raise productivity across the economy. Human capital, the skills and knowledge built through education, training and health, raises worker productivity and helps economies absorb new technology. Research and development pushes out the frontier in developed economies, while developing economies gain most by adopting existing technology. The trap is assuming all investment is equally productive: a high investment rate in low-return projects adds little, and new equipment is poorly used without skilled workers.