Torricelli S Law — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.
Torricelli's Law Applies to ideal, incompressible, non-viscous fluids flowing from an open tank through a small orifice under the influence of gravity. Start with Bernoulli's Principle: P1 + 0.5 rho v1 2 + rho g h1 = P2 + 0.5 rho v2 2 + rho g h2. Set P1 = P2 = P atm (both open to air). Assume v1 approx 0 (tank area >> orifice area). Simplify to rho g h1 = 0.5 rho v2 2 + rho g h2. Rearrange: g(h1 - h2) = 0.5 v2 2. Let h = h1 - h2. Solve for v2. The area of the orifice must be much smaller than the cross-sectional area of the tank. The fluid must be inviscid (zero viscosity). The tank must be open to the atmosphere (or pressures equalized). Flow is steady and streamline. Thinking h is the height from the bottom of the tank (it is depth from the surface). Assuming the law holds for viscous fluids like honey. Thinking the horizontal range of the jet depends only on v (it also depends on the height of the hole from the ground).