Calculating Heat Flow Through a Block of Material

AI Thread Summary
The discussion revolves around calculating the rate of heat flow through a block of wood with a specified cross-sectional area and temperature difference. The formula used is P = KA(ΔT)/L, where the values for area and length were converted to meters. The initial calculation yielded 4.5 Watts, while the book states the answer is 5.6 Watts. Participants suggest that the discrepancy may stem from unit conversion errors, particularly a factor of 1000. The conversation highlights the importance of double-checking calculations and unit conversions in physics problems.
mizzy
Messages
217
Reaction score
0

Homework Statement


A block of material with a cross sectional area of 15cm^2 and length of 8cm is at hand. A temperature difference of 30degrees is established and maintained across the block. Find the rate of heat flow through it if the material is wood (K = 0.08Js-1m-1C-1)


Homework Equations



P = KA(change in T)/L

The Attempt at a Solution


P is watts. I converted area and length into meters.

Everything is given, all i need to do is plug in the values. I did that and I get 4.5 Watts. The answer in the back of the book is 5.6W.

Can someone do the calculation and confirm it with me? Either it's an error in the book or I'm missing something.

THANKS! :smile:
 
Physics news on Phys.org
I plugged the values exactly as given into my calculator, and I get an answer that differs from yours by a factor of 1000. I'd suggest double-checking your unit conversions.

I really don't know where the 5.6W in the back of the book might have come from, unless there's something more to the problem - but I can't think of what that might be.
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top