Can the weight of heat be accurately measured in such small increments?

In summary, the conversation discusses the relationship between temperature increase and mass increase in 1 kg of gold, as well as the use of the formula E=mc^2 to calculate the energy required for this increase. The conversation also touches on the concept of specific heat capacity and the importance of specifying physical units in calculations.
  • #1
alba
140
4
I read that if the temperature of 1 Kg of gold rises by 10°C its mass increases by 1.4 * 10^-14 kg.
Can you please explain how you get such value from E= mc^2?
I think the increase corresponds to E = h f =1.53*10*10^36 and since
1 kg has 1.1*10^30 electrons, each one gets 1.4*10*6 h
but
10 degrees correspond to energy E = h f = 2.8*10^11 h)

so shouldn't the increase of energy be 2.29*10 ^41 h?

Can you also tell what instrument can measure the weight o 10^-14 Kg and what is the minimal weight that can be detected?
 
Science news on Phys.org
  • #2
It is completely unclear what you are trying to do. E=hf is the energy content of a photon and has absolutely nothing to do with the mass increase of the gold. You need to figure out how much energy needs to be added and compute the corresponding mass increase.
 
  • #3
Orodruin said:
It is completely unclear what you are trying to do. E=hf is the energy content of a photon and has absolutely nothing to do with the mass increase of the gold. You need to figure out how much energy needs to be added and compute the corresponding mass increase.
E = 1.4*10-14* 9*10^16 = 12 = 1260 J
The energy of a joule can be expressed in many ways, in eV or in h*Herz 1260 /h = 1.9*10 ^36
what is the problem? that is the energy added, I cannot figure out how that relates to T = +10*C

Any ideas?
 
  • #4
alba said:
The energy of a joule can be expressed in many ways, in eV or in h*Herz 1260 /h = 1.9*10 ^36
what is the problem?
Which units you use are unrelated to how you solve the problem. There is no point in using E=hf here.

alba said:
E = 1.4*10-14* 9*10^16 = 12 = 1260 J
Just putting numbers is not a very good way to present a solution. First write down the physical relation you are using, then write down what numbers you are putting in (including units!).

alba said:
that is the energy added, I cannot figure out how that relates to T = +10*C
The energy added must depend on the temperature increase. If yours does not, it is wrong.
 
  • #6
To understand how to calculate the "heat" energy required to raise the temperature of something, read this: Specific Heat
 
  • #7
Thank you very much for the links, so:
c for gold is 0.126 J/gmK 1000g, therefore 1000g*10 K makes 1260 J (1.5*10^36 hv), right?
 
  • #8
alba said:
c for gold is 0.126 J/gmK 1000g, therefore 1000g*10 K makes 1260 J
1260 J looks good to me.

alba said:
(1.5*10^36 hv)
What's this?
 
  • #9
Doc Al said:
1260 J looks good to me.
What's this?
Is it so weird to refer to energy by Hz? 1 J equals 1.5*10^33 h/s, right?

Can you tell me if the weight increase is just deduced from the formula, or if it is (and to what precison) confirmed my measurement?
 
  • #10
alba said:
Is it so weird to refer to energy by Hz?

It simply does not make any sense. You could do this by using units of ##\hbar## but this is normally done in particle physics and this is not.
Also, in your answer you are referring to ##hf##. This makes no sense at all unless you specify what ##f## is.
 
  • Like
Likes alba
  • #11
alba said:
I read that if the temperature of 1 Kg of gold rises by 10°C its mass increases by 1.4 * 10^-14 kg.
Can you please explain how you get such value from E= mc^2?
alba said:
c for gold is 0.126 J/gmK 1000g, therefore 1000g*10 K makes 1260 J
So now you know E (or more precisely, the amount by which the E of the gold increases when its temperature increases by 10°C). Now, what m does this give you?
 
  • #12
Orodruin said:
This makes no sense at all unless you specify what ##f## is.
You must have missed that, in my first post I specified
f =1.53*10*10^36
 
  • #13
alba said:
You must have missed that, in my first post I specified
This is completely besides the point. You cannot just arbitrarily select a frequency.

Apart from that, your "frequency" is not a frequency, it is a number. A number is meaningless without the appropriate physical units.
 

Related to Can the weight of heat be accurately measured in such small increments?

1. What is the weight of heat?

The weight of heat refers to the amount of thermal energy contained in a substance or system. It is measured in units of joules or calories.

2. How does heat affect the weight of an object?

When heat is added to an object, its weight may increase slightly due to the increased kinetic energy of its molecules. However, this change in weight is usually too small to be measured by standard scales.

3. Can heat be converted into weight?

No, heat cannot be converted into weight. Weight is a measure of the force of gravity on an object, while heat is a form of energy. However, heat can cause changes in the weight of an object by affecting its mass or density.

4. Does the weight of heat vary with temperature?

Yes, the weight of heat can vary with temperature. As temperature increases, the weight of heat also increases due to the increased kinetic energy of the molecules. This is known as thermal expansion.

5. How is the weight of heat measured?

The weight of heat is typically measured using a calorimeter, which is a device that measures the amount of heat released or absorbed during a chemical reaction or physical change. The amount of heat is then converted into units of weight using specific heat capacity or heat of fusion/vaporization values.

Similar threads

Replies
6
Views
1K
Replies
8
Views
1K
Replies
1
Views
672
Replies
19
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
9
Views
7K
  • Special and General Relativity
Replies
14
Views
2K
  • Special and General Relativity
Replies
24
Views
2K
  • Materials and Chemical Engineering
Replies
10
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
4
Views
1K
Back
Top