# Popeye Needs His Spinach

Popeye loves his spinach. He squeezes a can of his favorite spinach in such a way that it retains the shape of a cylinder and its volume remains constant, but the radius of the can decreases at $1 \text{ cm}$ per second.

How fast is the height of the can changing at the moment the can has a radius of $4 \text{ cm}$ and a height of $10 \text{ cm}?$

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