Recent content by UMath1

The equation is used to find the net radiative heat transfer to a given surface. It is typically used when modeling radiation systems as resistive networks. Ebi is the emissivity of the surface were it a blackbody while Ji is the actual radiosity of the surface. ε is the emissivity of the...

I've seen two different explanations on the working principle of DC motors: One considers the rotor as a loop of wire that experiences a torque because current flow is perpendicular to an external magnetic field. The other describes the loop as an electromagnet which then experiences a torque...

Can someone answer?

In that equation, Ebi is defined as the emission from a perfect blackbody and Ji is the radiosity.

What about equation 13.19 referenced above?

I'm referencing this equation from Fundamentals of Heat and Mass Transfer. It suggests that net radiation to a blackbody is zero because Ebi=Ji and ei=1.

So a black car can't be modeled as a blackboday? What about a vantablack surface? These are used for solar energy generation and also get hotter?

If rate of emission = rate of absorption for a blackbody, how can a blackbody undergo temperature change through radiation? How come black cars get hotter on a sunny day?

That makes sense. I still don't understand why ΔS must equal 0. What if the system continues to maintain the generated entropy? What would happen then?

In deriving the Carnot Efficiency, the assumption is made that theoretically most efficient engine will generate no net entropy, meaning that the entropy that enters the system during heat absorption must equal the entropy that leaves the engine during heat rejection. Why is the case? Why would...

If a beam is fixed at both end and subjected to nonuniform bending would the upper section of the beam still be in compression. My intuition and free body diagrams suggest it would but geometrically in this case, wouldn't all sections of the beam, even the upper section, have to elongate/curve...

Thank you for this. I am still somewhat confused. I understand that the calculations prove that the max shear stress is at the center of the flange. But understanding the directions of the stress with the fluid flow analogy does not seem concrete to me. Is there a free body diagram I can make to...

Where do the horizontal left to right shears arise from in the flange? I can visual transverse shears on a beam creating vertical shears on the web but I can't visualize the horizontal shears in the flange. Similarly, I am having trouble visualizing or creating a free body diagram to understand...

I have taken E&M, Newtonian Mechanics and Dynamics, and among the ME courses, I have taken Solids, Materials, and Thermodynamics.