Water falls from a height of 1200 m. How much will the water temperature rise if 60% of the work of gravity is spent on heating it?

Initial data: h (height of water fall) = 1200 m; η (the amount of energy that goes to heating water) = 60% = 0.6.

Reference values: g (acceleration due to gravity) = 10 m / s2; C (specific heat of water) = 4200 J / (kg * K).

The change in water temperature can be determined from the equality: Q = η * A: C * m * Δt = η * m * g * h, whence Δt = η * g * h / C.

Let’s calculate: Δt = 0.6 * 10 * 1200/4200 = 1.71 ºС.

Answer: The water temperature will rise by 1.71 ºС.