What is Torricelli’s Law?

If you pierce a container of fluid a distance $h$ below its surface level, the fluid (ignoring viscosity) will flow through the hole at a speed of $v = \sqrt{2gh}$.

This is the same as the speed at which a particle (ignoring air resistance) would attain after falling a distance $h$.

Why is it interesting?

Fluid dynamics is always interesting. Torricelli’s law is a neat early result in the field, a special case of Bernoulli’s principle.

Who was Evangelista Torricelli?

Torricelli was born in Rome, Italy on October 15th, 1608. He died, possibly of typhoid fever, in Florence shortly after his 39th birthday.

He studied under Galileo, apparently did loads of hydraulic and ballistic experiments, invented the barometer ((way to bury the lede, Beveridge)), and had several other things named after him – including the Torricelli Trumpet (or Gabriel’s horn) and Torricelli’s Equation ($v^2 = u^2 + 2as$).