Let's calculate how fast the water squirts from a hole punched in the side of a paper cup or other container of water. We make two simplifying assumptions: Follow the solution carefully. Notice that the density, rho, and gravity, g, are the same at the top and at the hole. The final equation is called Torricelli's Theorem. Torricelli came up with this theorem before Bernoulli developed his equation. Torricelli also used the concept of conservation of energy. He stated that the change in gravitational potential energy equals the change in kinetic energy. Let's check this. Set the gravitational potential energy of an object at a height, h, equal to the kinetic energy of the object after it falls a distance h.

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