1. The problem statement, all variables and given/known data A hydroelectric power plant is built next to a reservoir with a water turbine beneath a dam. In normal operation, which of the following conditions will increase the flow rate of water, in kg s^-1 ,through the turbine. (1) There are too much water in the reservoir. (2) After a heavy rainfall (3) There is an increase in the demand of electricity A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only 2. Relevant equations The answer is B. flow rate = p A v Power output max = p A v g h where p is the density of water, A is the cross sectional area of the turbine, v is the speed of water. 3. The attempt at a solution I know that (1) is incorrect because the gates will be opened to release the excessive water. (3) is correct because the inlet to the turbine will be widened. flow rate = p A v, p and A are unchanged, so the velocity of water increases to increase the flow rate. However how should I explain (2), from my intuition the pressure difference increases because there is a higher water pressure due to pgh , speed of the water should increases which results in a larger flow rate, why is the flow rate unchanged?