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## Homework Statement

Particle goes to free fall from point ##A## to point ##B##. ##\upsilon_{A}=0##. How to define law of conservation of energy. Coordinate system is selected in such way that ##y## coordinate od point ##A## is zero. (See figure energy)

## Homework Equations

For free fall ##\upsilon_{B}=\sqrt{2gy}##.

## The Attempt at a Solution

My problem is with formulation of law of conservation of energy. Energy of point ##A## is in this case ##0##? Right? Because potential energy is zero (##y## cordinate of point ##A## is zero) and in case of free fall ##\upsilon_{A}=0##.

And energy of point ##B## is also zero ##-mgy+m\frac{\upsilon^2}{2}=0##.

Am I right? I'm confused how the energy of the particle could be zero? Can you help me? Give me some other view?