Heat and max temperature Problem

Click For Summary
The discussion centers on whether tomorrow's maximum temperature of 28°C is twice as hot as today's maximum of 14°C. It is clarified that temperature scales like Celsius are not absolute, making direct comparisons misleading. By converting the temperatures to Kelvin, 14°C becomes 287K and 28°C becomes 301K, revealing that 28°C is only about 5% hotter than 14°C. The conclusion is that to be "twice as hot," one must use the Kelvin scale, where 301K is not double 287K. Thus, the initial assumption that 28°C is twice as hot as 14°C is incorrect.
someone1029
Messages
5
Reaction score
0
[SOLVED] Heat Problem

The question is:

If today's maximum temperature was 14°C and tomorrow's maximum is expected to be 28°C, will tomorrow be twice as hot as today. Explain your answer.

The only equations known are Q=mcΔT, and Q=ml
Where Q= energy in joules. m=mass in kg, c= specific heat capacity [to 3 decimal places], ΔT= the change in temperature in either kelvin or Celsius, l= latent heat [also to 3 decimal places]

However I am not limited to these equations, just expected to use them. Use of other equations is fine, so long as they are within reason.

My train of thought was that, I need to find out and compare how many watts of heat will be absorbed by an identical body of mass over the same period of time at the two different temperatures, i just don't know how. I also think that this is one of those questions designed to trick, or at least make you really think. So I think that the short answer to the question is no, I just can't prove this right or wrong.

I have tried taking a theoretical 1kg aluminium block and putting them into each of the temperatures resulting in these equations:

8.90e+3*14=124600
8.90e+3*28=249200
as 249200 is 2*124600 then it is twice as hot

However I do not think this is right as these values are the amount of energy required to make this temperature change. Am I on the right track, or am I nowhere near the answer?
 
Physics news on Phys.org
Think about this: is zero degress C the bottom of the celsius temperature scale?
 
No it isn't, -273°c is. Can you please explain the relevance of this though? I just chose 0°c as a point from which the blocks would get heated. If you convert the temperatures to kelvin you get exactly the same results.
 
14\circC is 14 + 273 = 287 degrees above absolute zero. 28\circC is 28 + 273 = 301 degrees above absolute zero.

Now \frac{301}{287} = about 1.05, and so 28\circC is about 5% hotter than 14\circ, not twice at hot.

A temperature of 2(287) - 273 = 301\circC is twice as hot as 14\circC.

The celsius scale is not an absolute T scale. The kelvin scale is. 0K is absobute zero and so, for example, 300K is twice as hot as 150K.
 
Ok, I was just trying to over complicate things, as usual. Now that I look back at the problem I see how simple it is. Thanks for your help, no doubt I will call on it again some time in the future.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

Similar threads

  • · Replies 2 ·
Replies
2
Views
706
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
Replies
4
Views
2K
Replies
11
Views
2K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 33 ·
2
Replies
33
Views
2K
Replies
25
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 13 ·
Replies
13
Views
3K