Solution:
Energy absorbed by ice $= \frac{1}{4} mgh$. This energy melts the ice, so $\frac{1}{4} mgh = mL$. Substituting values: $h = \frac{4L}{g} = \frac{4 \times 3.4 \times 10^5}{10} = 13.6 \times 10^4\text{ m} = 136\text{ km}$.
A piece of ice falls from a height $h$ so that it melts completely. Only one-quarter of the heat produced is absorbed by the ice and all energy of ice gets converted into heat during its fall. The value of $h$ is [Latent heat of ice is $3.4 \times 10^5\text{ J/kg}$ and $g = 10\text{ N/kg}$]: (2016 - I)
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