Find the rate at which its temperature changes

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SUMMARY

The discussion revolves around calculating the rate of temperature change for a solid copper sphere with a radius of 5.70 cm in a vacuum, initially at 0.0°C, while surrounded by walls at 21.0°C. The participant used the formula Pnet = dQ/dt = mc dT/dt and derived dT/dt = [3eσ(T^4 – T0^4)]/rρc, but encountered issues with the computer system not accepting the answer. The solution emphasizes the importance of verifying calculations and ensuring unit consistency to resolve discrepancies.

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ive been working on this problem and i have a solution too, but it doenst work. the reason i know that it doesn't work is because we have to submit our answers to a computer system that tells us if our answer is right or wrong. please help?

A blackened, solid copper sphere of radius 5.70 cm hangs in a vacuum in an enclosure whose walls have a temperature of 21.0°C. If the sphere is initially at 0.0°C, find the rate at which its temperature changes, assuming that heat is transferred by radiation only. Also assume that the sphere has an emissivity of 1.

here is what i did:

Pnet = dQ/dt = mc dT/dt

one two skip a few and...

dT/dt = [3eσ(T^4 – T0^4)]/rρc

its right...but it doenst work!

please help?
 
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never mind...i got it...
 


It seems like you have the right equation and approach to solving this problem. However, since you are having trouble with the answer not being accepted by the computer system, there may be a small error in your calculations or units. I would suggest double checking your work and making sure all units are consistent.

Additionally, if you are still having trouble, you can try reaching out to your instructor or classmates for help. Sometimes, having a fresh set of eyes can help identify any mistakes or misunderstandings. Good luck!
 

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