Calculating Net Heat Flow for an Aluminum Disk in a Room

[lonelypancreas]

Homework Statement

What is the net heat flow of an aluminum disk (emissivity = 0.05) with radius
10 cm and temperature 293K placed inside a room where the temperature is 300K?

A_surface = π*r² = 0.01π m²

Homework Equations

H_net = A*e*σ(T_radiate⁴-T_absorb⁴)

The Attempt at a Solution

By simply plugging in the values, I get a value of 0.13. However, the answer is not among the choices.

Where did I possibly go wrong?

 

[collinsmark]

Homework Statement

What is the net heat flow of an aluminum disk (emissivity = 0.05) with radius
10 cm and temperature 293K placed inside a room where the temperature is 300K?

A_surface = π*r² = 0.01π m²

Homework Equations

H_net = A*e*σ(T_radiate⁴-T_absorb⁴)

The Attempt at a Solution

By simply plugging in the values, I get a value of 0.13. However, the answer is not among the choices.

Where did I possibly go wrong?

That's the numerical answer that I got (don't forget to include your units in the future), with the possible exception of a negative sign.

What are the other choices?

 

[lonelypancreas]

That's the numerical answer that I got (don't forget to include your units in the future), with the possible exception of a negative sign.

What are the other choices?

 

[collinsmark]

View attachment 205786

Hmm. The given answer choices differ from our answer by a factor of around √2, for what that's worth.

Unless there's more to the problem though I think our answer of 0.13 W is correct*. I don't know, maybe it's a mistake in the book/coursework?

*I'll let you figure out if it's into or out of the disk.