Change the chapter
Question
(a) Cherry-red embers in a fireplace are at $850^\circ\textrm{C}$ and have an exposed area of 0.200 m2 and an emissivity of 0.980. The surrounding room has a temperature of $18.0^\circ\textrm{C}$. If 50% of the radiant energy enters the room, what is the net rate of radiant heat transfer in kilowatts? (b) Does your answer support the contention that most of the heat transfer into a room by a fireplace comes from infrared radiation?
1. $8.80\times 10^{3}\textrm{ W}$
2. Compare to conduction: if we assume that heat conducted 1 meter away from the coals will reach beyond the fireplace, and therefore enter the room rather than go up the chimney, then only 3.83 W would be conducted to the room. Radiation has a heat transfer rate that is greater than that by conduction by a factor of 2300.
Solution Video

# OpenStax College Physics for AP® Courses Solution, Chapter 14, Problem 56 (Problems & Exercises) (2:38)

Rating

No votes have been submitted yet.

Quiz Mode

Why is this button here? Quiz Mode is a chance to try solving the problem first on your own before viewing the solution. One of the following will probably happen:

1. You get the answer. Congratulations! It feels good! There might still be more to learn, and you might enjoy comparing your problem solving approach to the best practices demonstrated in the solution video.
2. You don't get the answer. This is OK! In fact it's awesome, despite the difficult feelings you might have about it. When you don't get the answer, your mind is ready for learning. Think about how much you really want the solution! Your mind will gobble it up when it sees it. Attempting the problem is like trying to assemble the pieces of a puzzle. If you don't get the answer, the gaps in the puzzle are questions that are ready and searching to be filled. This is an active process, where your mind is turned on - learning will happen!
If you wish to show the answer immediately without having to click "Reveal Answer", you may . Quiz Mode is disabled by default, but you can check the Enable Quiz Mode checkbox when editing your profile to re-enable it any time you want. College Physics Answers cares a lot about academic integrity. Quiz Mode is encouragement to use the solutions in a way that is most beneficial for your learning.

Video Transcript