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  4. The height of a waterfall is 84 m. Assuming that the entire kinetic energy of falling water is converted into heat, the rise in temperature of the water will be: (g=10 m s -2, J =4.2. joule/cal )

Q. The height of a waterfall is $84\, m$. Assuming that the entire kinetic energy of falling water is converted into heat, the rise in temperature of the water will be : $\left(g=10\, m s ^{-2}, J =4.2\right.$ joule/cal $)$

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Solution:

Kinetic energy of water is
$\frac{m \times 9.8 \times 84}{4.2} =m \times 1000 \times \Delta T$
$\Delta T =0.2^{\circ} C$

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