Find the rate at which its temperature changes

  • Thread starter Thread starter jbot2222
  • Start date Start date
  • Tags Tags
    Rate Temperature
AI Thread Summary
The discussion revolves around calculating the rate of temperature change for a copper sphere in a vacuum, initially at 0.0°C, with surrounding walls at 21.0°C. The user initially believes they have the correct formula but finds their answer is not accepted by the computer system. Suggestions include double-checking calculations and ensuring unit consistency, as minor errors could lead to incorrect results. Additionally, seeking assistance from instructors or peers may help resolve any misunderstandings. Ultimately, verifying each step in the calculation process is crucial for achieving the correct answer.
jbot2222
Messages
14
Reaction score
0
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?
 
Physics news on Phys.org
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!
 

Thread 'Errors and significant figures'

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...
View full post »
Thread 'A cylinder connected to a hanging mass'

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...
View full post »

Similar threads

Find rate of temperature change using heat capacity, density and area
Replies
4
Views
2K
Change in Entropy When Mixing Water at Different Temperatures
Replies
5
Views
1K
Temperature as a function of time in black body radiation
Replies
14
Views
2K
Steady state heat flow: radiation and conduction
Replies
5
Views
3K
Specific heat capacity of a metal at low temperature
Replies
8
Views
6K
Fluid's temperature change in time.
Replies
3
Views
1K
What is the equilibrium temperature of a collector plate?
Replies
2
Views
3K
Using Pressure and Temperature differences to find height
Replies
3
Views
2K
How much heat required to raise the temperature of potassium
Replies
1
Views
1K
Rate at which Sun converts mass to radiation
Replies
14
Views
2K

Hot Threads

Recent Insights

Back
Top