- #1
PotatoMerchant
- 1
- 0
Homework Statement
Homework Equations
(unsure)
Rate of Heat Transfer for a Two-Layer System
- Thread starter PotatoMerchant
- Start date
-
- Tags
- Heat Heat transfer Rate
AI Thread Summary
The discussion centers on the correct approach to calculating heat transfer in a two-layer system. The initial equation presented is deemed incorrect, and the correct formula for a single layer is provided as 2πrLq = Q = 2πkL(ΔT/Δlnr). This formula is applicable to each concentric layer, drawing an analogy to resistors in series, where the temperature difference (ΔT) represents the voltage drop. The goal is to determine the overall heat flow (Q) given the total temperature difference of 155 C across both layers. Understanding these principles is crucial for accurately solving the problem.
(unsure)
- #2
- 23,704
- 5,917
It doesn't look like this has been done correctly. To begin with, the starting equation is incorrect.
For a single layer, it should read:
2πrLq =Q=2πkL\frac{ΔT}{Δlnr}
where Q is the total heat flow (watts) and q is the heat flow per unit area. This equation applies to each of the concentric layers. The problem is analogous to having two resistors in series, where ΔT is like the voltage drop across each layer and Q is the current flow through the resistors. You have to solve for the current flow, given the overall voltage drop across both layers (155 C).
For a single layer, it should read:
2πrLq =Q=2πkL\frac{ΔT}{Δlnr}
where Q is the total heat flow (watts) and q is the heat flow per unit area. This equation applies to each of the concentric layers. The problem is analogous to having two resistors in series, where ΔT is like the voltage drop across each layer and Q is the current flow through the resistors. You have to solve for the current flow, given the overall voltage drop across both layers (155 C).
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...
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...
This problem is two parts. The first is to determine what effects are being provided by each of the elements - 1) the window panes; 2) the asphalt surface. My answer to that is
The second part of the problem is exactly why you get this affect.
And one more spoiler:
Similar threads
Hot Threads
-
Collision of a bullet on a rod-string system: query
- Started by palaphys
- Replies: 71
- Introductory Physics Homework Help
Recent Insights
-
Insights Quantum Entanglement is a Kinematic Fact, not a Dynamical Effect
- Started by Greg Bernhardt
- Replies: 7
- Quantum Physics
-
Insights What Exactly is Dirac’s Delta Function? - Insight
- Started by Greg Bernhardt
- Replies: 0
- General Math
-
Insights Relativator (Circular Slide-Rule): Simulated with Desmos - Insight
- Started by Greg Bernhardt
- Replies: 1
- Special and General Relativity
-
Insights Fixing Things Which Can Go Wrong With Complex Numbers
- Started by PAllen
- Replies: 7
- General Math
-
Insights Fermat's Last Theorem
- Started by fresh_42
- Replies: 91
- General Math
-
Insights Why Vector Spaces Explain The World: A Historical Perspective
- Started by fresh_42
- Replies: 0
- General Math