Question

Initial temperatures of a metallic sphere and a
disc of same radius and same nature are same
The ratio of their rates of cooling will be
(a) 1:4
(b) 4:1
(C) 2:1
(d) 1:2​

Answer 1

➭ Questíon :-

$⟶$ Initial temperatures of a metallic sphere and a disc of same radius and same nature are same The ratio of their rates of cooling will be

(a) 1:4

(b) 4:1

(☑) 2:1

(d) 1:2

➭ Solution :-

$⟹ E = {AT}^{4} \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ ⟹ \frac{ E_{sphere} }{ E_{disc}} \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ ⟹ \frac{4\pi {r}^{2} }{2\pi {r}^{2} } \times { \frac{1}{1} }^{4} = \frac{2}{1} \: \: \:$

$⟹$ $\boxed{\sf 2 : 1}$

hence, Option (c) is correct