A solid copper cube of edges 1 cm is suspended in an evacuated enclosure. Its temperature is found to fall from `100^@C` to `99^@C` in 100 s. Another solid copper cube of edges 2 cm, with similar surface nature, is suspended in a similar manner. The time required for this cube to cool from `100^@C` to `99^@C` will be approximatelyA. 25 sB. 50 sC. 200 sD. 400 s

A solid copper cube of edges 1 cm is suspended in an evacuated enclosu

1.	A solid copper cube of edges 1 cm is suspended in an evacuated enclosure. Its temperature is found to fall from `100^@C` to `99^@C` in 100 s. Another solid copper cube of edges 2 cm, with similar surface nature, is suspended in a similar manner. The time required for this cube to cool from `100^@C` to `99^@C` will be approximatelyA. 25 sB. 50 sC. 200 sD. 400 s
Answer» Correct Answer - C `(dT)/(dt)=(eAsigma)/(mc)(T^4-T_0^4)=(e(6a^2)sigma)/((a^3xxrho)c)(T^4-t_0^4)` `implies` for the same fall in temperature time `dtpropa` `(dt_2)/(dt_1)=(a_2)/(a_1)=(2cm)/(1cm)impliesdt_2=2xxdt_1=2xx100s=200s` (As `A=6a^2` and `m=Vxxrho=a_3xxrho`)

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