The stepped cylindrical tank is initially filled with liquid water at STP to a height H1. Subsequently, a plug at the bottom of the tank is removed to allow water to flow from the small hole of diameter d. The velocity v of the flowing water can be related to the instantaneous height of the water above it h(t) based on an adjusted mechanical energy conservation relationship; 1/2mv^2 = 0.96mgh . Develop an expression for the time to drain the tank based on given parameters and then evaluate the time to drain if D1=60cm, D2=35cm, H1=70cm, H2=30cm and d=6mm