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    				| 1. | A cylindrical vessel of height h and base area S is filled with water. An orifice of area `s lt lt S` is opened in the bottom of the vessel. Neglecting the viscosity of water, determine how soon all the water will pour out of the vessel. | 
| Answer» Let at any moment of time, water level in the vessel be H then speed of flow of water through the orifice, at that moment will be `v=sqrt(2gH)` (1) In the time interval `dt`, the volume of water ejected through orifice, `dV=svdt` (2) On the other hand, the volume of water in the vessel at time t equals `V=SH` Differentiating (3) with respect to time, `(dV)/(dt)=S(dH)/(dt)` or `dV=SdH` (4) Eqs. (2) and (4) `SdH=svdt` or `dt=S/s(dH)/(sqrt(2gH))` from (2) Integrating `underset(0)overset(t)intdt=(S)/(ssqrt(2h))underset(h)overset(0)int(dh)/(sqrtH)` Thus, `t=S/ssqrt((2h)/(g))` | |