Thermal Properties of Matter - Result Question 15

15. 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 :

[2016]

[Latent heat of ice is $3.4 \times 10^{5} J / kg$ and $g=10 N /$ $kg]$

(a) $34 km$

(b) $544 km$

(c) $136 km$

(d) $68 km$

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Answer:

Correct Answer: 15. (c)

Solution:

  1. (c) According to question only one-quarter of the heat produced by falling piece of ice is absorbed in the melting of ice.

i.e., $\frac{mgh}{4}=mL$

$\Rightarrow h=\frac{4 L}{g}=\frac{4 \times 3.4 \times 10^{5}}{10}=136 km$.