land,labor,and capital (2)

3- Capital goods, produced by the economic system itself to be used as productive inputs for further production of goods and services . these capital goods, which are both outputs and input,can be long-or-sort-lived. they can be rented out in the competitive market just the way acres of land or hours of labor can be. these rents -or perhaps we might use the term " rentals," to avoid confusion with pure economic rent to land in fixed supply-these rentals of capital goods are traditionally supposed to be determined by the same demand conditions of marginal productivity discussed previously
however, in the traditional capital theory, the return or yield of capital is not taken to be the rentals of capital goods. what,then , is it ?
The yield of capital is the interest rate per annum ,which is a pure percentage per unit time-independent of dollars or other values units. Of what is the interest rate 5 per cent per annum the yield? Obviously, it is the yield applied to the dollar value of capital goods.