The marginal physical productivity of labor is defined as January 1, 2023 by admin a firm’s total output divided by total labor input. the extra output produced by employing one more unit of labor while allowing other inputs to vary. the extra output produced by employing one more unit of labor while holding other inputs constant. the extra output produced by employing one more unit of capital while holding labor input constant. See Answer the extra output produced by employing one more unit of labor while holding other inputs constant.