Solution to 2001 Problem 35

The relevant formula is the Stefan-Boltzman formula:

\begin{align*}\frac{\Delta Q}{\Delta t} = \sigma \epsilon A T^4\end{align*}
Here, \Delta Q/\Delta t is the rate at which energy is radiated from the blackbody, \sigma is the Stefan-Boltzmann constant, \epsilon is the emissivity of the blackbody (which is equal to 1 for an ideal Blackbody), A is the area of the blackbody, and T is the temperature in Kelvin.

Replacing T by 3 T therefore increases the rate at which energy is radiated by a factor of 3^4 = 81. So, answer (E) is correct.

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