In a room where temperature is {30^o}C , a body cools from {61^o}C to {59^o}C in 4 minutes. time (in

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10-2.Transmission of Heat

normal

In a room where the temperature is ${30^o}C$, a body cools from ${61^o}C$ to ${59^o}C$ in $4$ minutes. The time (in min.) taken by the body to cool from ${51^0}C$ to ${49^0}C$ will be ....... $\min$

A$4$

B$6$

C$5$

D$8$

Solution

(b) First case, $\frac{{61 – 59}}{4} = K\left[ {\frac{{61 + 59}}{2} – 30} \right]$…..$(i)$
Second case, $\frac{{51 – 49}}{t} = K\left[ {\frac{{51 + 49}}{2} – 30} \right]$ …..$(ii)$
By solving equation $(i)$ and $(ii)$ we get
$t = 6 min$ .

Standard 11

Physics

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normal

In a room where the temperature is ${30^o}C$, a body cools from ${61^o}C$ to ${59^o}C$ in $4$ minutes. The time (in min.) taken by the body to cool from ${51^0}C$ to ${49^0}C$ will be ....... $\min$

Solution

Similar Questions

Two circular discs $A$ and $B$ with equal radii are blackend. They are heated to same temperature and are cooled under identical conditions. What inference do you draw from their cooling curves ?

The radiant energy from sun incident normally at the surface of earth is $20\, k\,cal/m^2- min$. What would have been the radiant energy incident normally on the earth if the sun had a temp. twice of the present one ? ……….. $k\,cal/m^2- min$

Two identical rods of copper and iron are coated with wax uniformly. When one end of each is kept at temperature of boiling water, the length upto which wax melts are $8.4\, cm$ amd $4.2\, cm$, respectively. If thermal conductivity of copper is $0.92$, then thermal conductivity of iron is

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