A body takes 5 minute to cool from 80°C to 50°C . ...... min. it will take to cool fro

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10-2.Transmission of Heat

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A body takes $5$ minute to cool from $80°C$ to $50°C$ . ...... $\min.$ it will take to cool from $60°C$ to $30°C$ , if room temperature is $20°C$ .

$40$

$9$

$30$

$20$

Solution

(b) According to Newton’s law of cooling
in first case,$\frac{{80 – 50}}{5} = K\left[ {\frac{{80 + 50}}{2} – 20} \right]$…..$(i)$
in second case,$\frac{{60 – 30}}{t} = k\left[ {\frac{{60 + 30}}{2} – 20} \right]$ $(ii)$
Dividing equation $(i)$ by $(ii)$ we get, $\frac{t}{2} = \frac{{45}}{{25}}$==>$t = 9$min.

Standard 11

Physics

The temperature of a liquid drops from $365K$ to $361 K$ in $2$ minutes. Find the time during which temperature of the liquid drops from $344\;K$ to $342K$. Temperature of room is $293\;K$ ……. $\sec$

hard

Cooling rate of a sphere of $600\,K$ at external environment $(200\,K)$ is $R$ . When the temperature of sphere is reduced to $400\,K$ then cooling rate of the sphere becomes

medium

A body takes $4\, {min}$. to cool from $61^{\circ} {C}$ to $59^{\circ} {C}$. If the temperature of the surroundings is $30^{\circ} {C}$, the time taken by the body to cool from $51^{\circ} {C}$ to $49^{\circ} {C}$ is $….\,min$

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(JEE MAIN-2021)

Liquid cools from $50^oC$ to $45^oC$ in $5\ minutes$ and from $45^oC$ to $41.5^oC$ in the next $5\ minutes$.The temperature of the surrounding is ……… $^oC$

easy

Discuss the experiment verifying Newton's law of cooling.

hard

A body takes $5$ minute to cool from $80°C$ to $50°C$ . ...... $\min.$ it will take to cool from $60°C$ to $30°C$ , if room temperature is $20°C$ .

Solution

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