An ice box used for keeping eatable cold has a total wall area of 1metr{e^2} and a wall thickness of

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10-2.Transmission of Heat

medium

An ice box used for keeping eatable cold has a total wall area of $1\;metr{e^2}$ and a wall thickness of $5.0cm$. The thermal conductivity of the ice box is $K = 0.01\;joule/metre{ - ^o}C$. It is filled with ice at ${0^o}C$ along with eatables on a day when the temperature is $30°C$ . The latent heat of fusion of ice is $334 \times {10^3}joules/kg$. The amount of ice melted in one day is ........ $gms$ ($1day = 86,400\;\sec onds$)

$776$

$7760$

$11520$

$1552$

(d) $\frac{{dQ}}{{dt}} = \frac{{KA}}{l}d\theta $ $ = \frac{{0.01 \times 1}}{{0.05}} \times 30$ $= 6J/sec$

Heat transferred in on day ($86400 sec$)

$\theta = 6 \times 86400 = 518400\,J$

Now $Q = mL$ $⇒$ $m = \frac{Q}{L}$$ = \frac{{518400}}{{334 \times {{10}^3}}}$

$= 1.552 kg = 1552g.$

Standard 11

Physics

medium

medium

(AIPMT-2003)

hard

easy

(AIIMS-1999)

easy