Is a Rate of 100K/s an Intuitively Offensive Way to Measure Temperature Change?

[Bolter]

Homework Statement

Thermal physics

Relevant Equations

Q=m*c*deta t

Question:

This would be the right approach to do this problem?

Thanks!

 

[Bystander]

Homework Statement:: Thermal physics
Homework Equations:: Q=m*c*deta t

Question:

View attachment 253759
This would be the right approach to do this problem?
View attachment 253760

Thanks!

Correct approach. Incorrect result.

 

[Bolter]

Correct approach. Incorrect result.

Why is it an incorrect result?

 

[TSny]

Why is it an incorrect result?

I think your answer is correct. I hope I'm not overlooking something trivial.

 

[Bystander]

Three orders of magnitude too large.

 

[TSny]

Three orders of magnitude too large.

Note that the power input is given in kilowatts.

 

[Bystander]

in kilowatts.

..., and mass in kilograms.

 

[TSny]

..., and mass in kilograms.

Yes. From m and c you can see that it takes about 100 J to raise T by 1 K. Heat is going in at about 10,000 J each second. So T will increase about 100 K each second.

 

[Bystander]

. Looking at the faint decimal point in "nine point eight one" and figuring he'd missed that in his computation; wasn't paying attention...100K/s? Intuitively offensive, but...

 

[TSny]

...100K/s? Intuitively offensive

Yes. That rate of heating would not last long.