A) \[1:4\]
B) \[4:1\]
C) \[1:2\]
D) \[2:1\]
Correct Answer: D
Solution :
From Newton's law of cooling, the rate of loss of heat by a body is proportional to the temperature difference between the body and its surroundings and is given by Rate of loss heat \[=Area\times [T'-T]\] Area of sphere \[=4\pi {{r}^{2}},\] area of disc \[=2\pi {{r}^{2}}\] \[\therefore \] \[\frac{Rate\text{ }of\text{ }cooling\text{ }of\text{ }sphere}{Rate\text{ }of\text{ }cooling\text{ }of\text{ }disc}=\frac{4\pi {{r}^{2}}}{2\pi {{r}^{2}}}=\frac{2}{1}\]
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