Final answer:
Constantly increasing factors like population growth and physical capital can increase the internal rate of growth, but the marginal gains to economic growth will diminish over time.
Step-by-step explanation:
Constantly increasing factors such as population growth and physical capital can increase the internal rate of growth. However, the law of diminishing returns suggests that the marginal gains to economic growth will diminish as these factors continue to increase. For example, increasing the average education level or physical capital will initially lead to a certain increase in output, but the marginal gain will become smaller with each subsequent increase.