For the manufacturing of one day’s paper products a paper mill uses the necessary coal, oil, chemicals, and wood that are already stored in the mill. In addition, some of the energy needed in the mill is obtained from a waterfall of 10 6 kg of water per day falling over a difference in elevation of 100 m. Assume that the mill experiences no interactions except that with the waterfall.
(a) What is the change in energy of the mill after 1 day of paper production?
(b) At a particular day the waterfall is interrupted and the mill uses half its wood as fuel rather than feedstock for paper. What is the change in energy of the mill during that day? the energy that is made available from the burning wood is 18,000 kJ/kg, and paper requires 40,000 kJ per kg of paper.