A solid copper sphere (density $$\rho $$ and specific heat capacity c) of radius r at an initial temperature 200K is suspended inside a chamber whose walls are at almost 0K. The time required (in $$\mu $$s) for the temperature of the sphere to drop to 100 K is [IIT-JEE 1991]

Question

A solid copper sphere (density $$\rho $$ and specific heat capacity c) of radius r at an initial temperature 200K is suspended inside a chamber whose walls are at almost 0K. The time required (in $$\mu $$s) for the temperature of the sphere to drop to 100 K is                                  [IIT-JEE 1991]

TuteeHUB · Accepted Answer

$$\frac{27}{7}\frac{r\rho c}{\sigma }$$

TuteeHUB · Answer

$$\frac{72}{7}\frac{r\rho c}{\sigma }$$

TuteeHUB · Answer

$$\frac{7}{72}\frac{r\rho c}{\sigma }$$

TuteeHUB · Answer

$$\frac{7}{27}\frac{r\rho c}{\sigma }$$

1.	A solid copper sphere (density \[\rho \] and specific heat capacity c) of radius r at an initial temperature 200K is suspended inside a chamber whose walls are at almost 0K. The time required (in \[\mu \]s) for the temperature of the sphere to drop to 100 K is [IIT-JEE 1991]
A.	\[\frac{72}{7}\frac{r\rho c}{\sigma }\]
B.	\[\frac{7}{72}\frac{r\rho c}{\sigma }\]
C.	\[\frac{27}{7}\frac{r\rho c}{\sigma }\]
D.	\[\frac{7}{27}\frac{r\rho c}{\sigma }\]
Answer» C. \[\frac{27}{7}\frac{r\rho c}{\sigma }\]

A solid copper sphere (density \[\rho \] and specific heat capacity c) of radius r at an initial temperature 200K is suspended inside a chamber whose walls are at almost 0K. The time required (in \[\mu \]s) for the temperature of the sphere to drop to 100 K is [IIT-JEE 1991]

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