Question

One end of metal bar of area of cross section $5c{m}^2$ and $25cm$ in length is in stream and other end is in contact with ice. The amount of ice melts in one minute is :

$(L=80cal/gm,K=0.8cgsunits)$

• A. $16gm$
• B. $12gm$
• C. $24gm$
• D. $36gm$

Answer 1

The correct option is B $12gm$

Given,

$K=0.8cgs$ unit

$L=80cal/gm$

$A=5c{m}^2$

$l=25cm$

$dT={100}^0$

$t=1min=60sec$

Rate of flow of heat,

$q=\frac{Q}{t}=KA\frac{dT}{dx}$. . . . .(1)

We know that, $Q=mL$

equation (1) becomes,

$\frac{mL}{t}=KA\frac{dT}{dx}$

$\frac{80m}{60}=0.8\times 5\times \frac{100}{25}$

$m=12gm$

The correct option is B.