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\[=2\pi {{r}^{2}}\] \[\therefore \] \[\frac{Rate\text{ }of\text{ }cooling\text{ }of\text{ }sphere}{Rate\text{ }of\text{ }cooling\text{ }of\text{ }disc}=\frac{4\pi {{r}^{2}}}{2\pi {{r}^{2}}}=\frac{2}{1}\]
You need to login to perform this action.
You will be redirected in
3 sec
