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**What I know:**Below link is about Torricelli's law. Velocity of liquid coming out of bottom of the tank i.e comes after using Bernoulli's equation square root of (2*g*h*) where "h" is height of fluid in the container and "g" is acceleration due to gravity.

https://en.wikipedia.org/wiki/Torricelli's_law

**Doubt:**All the time problem was given with the case of open container. That means gauge pressure is zero on the top of the surface of liquid and at bottom of the tank. Now this is the case with tank is with lid closed. Now what I think; we cannot neglect the pressure term in the Bernoull's equation because it would be the function of the height of fluid being reduced. As tank is being emptied; the density of air above the liquid is reducing so the pressure.

Then another doubt comes what if there is increase in the rate of evaporation and maintaining the density of air above liquid surface.

Pls help me to find out the expression of outlet velocity; I know it would be decreasing with the passage of time.

https://en.wikipedia.org/wiki/Torricelli's_law