Heat transfer between two iron blocks

In summary, the conversation discusses a problem involving calculating the final temperature of two blocks with different masses that have been heated to different temperatures. The person initially adds the temperatures and divides by 2, but realizes that this approach is not accurate due to the different masses. They then try to use the equation q=mcΔT, but struggle with understanding how to apply it in this situation. The conversation ends with a hint to consider the heat gained or lost by each block separately.
  • #1
ardour

Homework Statement


upload_2017-10-3_20-31-3.png


Homework Equations


I'm not sure.

The Attempt at a Solution


I tried to solve this as you would with electric charges. I added up the temperatures and then divided by 2, to get (C) 17.5 degrees Celsius. The answer key gives the answer as (D) 20.0 degrees Celsius. I'm not sure what equations you would use to get this.
 
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  • #2
Please try to figure out the relevant equations. This problem was not assigned to you out of the blue. It must have come at the end of a textbook chapter or lecture notes that surely contain some equations. Nevertheless, you can see why your answer is wrong because adding the temperatures and dividing by two will give the same final temperature regardless of the masses of the blocks. Does that sound reasonable? Hint: Yes, the final temperature is indeed some kind of average, but not the sum of temperatures divided by two.
 
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Likes Chestermiller
  • #3
+1

It won't be the average temperature because the masses aren't the same. However don't think your approach is totally wrong.
 
  • #4
Is q=mct the relevant equation? This question came from a practice test, so I'm not sure of the actual equation.

I tried setting mc(T-10) and 2mc(T-25) equal to each other, but got 40 for T. What am I doing wrong?
 
  • #5
The correct expression is ##Q=mc~\Delta T##, where ##\Delta T## is the change in temperature, final minus initial. Why do you think the quantities you set equal are equal? What is physically going on here?
 
  • #6
Q=mc ΔT

ΔT1= change in temperature for mass m
ΔT2= change in temperature for mass 2m

mcΔT1= 2mcΔT2
ΔT1=2ΔT2

The only answer which fits this is D, but I'm not sure how to calculate the temperature outright.
 
  • #7
ardour said:
mcΔT1=2mcΔT2
Can you explain in plain English and without symbols or equations what the two quantities that you are setting equal represent and why you think they are equal?

On Edit (Generous hint): Q stands for the heat gained by the mass. One mass gains heat heat, the other loses heat.
 

Related to Heat transfer between two iron blocks

1. How does heat transfer occur between two iron blocks?

Heat transfer between two iron blocks occurs through the process of conduction. This means that heat energy is transferred from one block to the other through direct contact between the two materials.

2. What factors affect the rate of heat transfer between two iron blocks?

The rate of heat transfer between two iron blocks is affected by the temperature difference between the blocks, the surface area of contact, the distance between the blocks, and the thermal conductivity of the materials.

3. Can the rate of heat transfer between two iron blocks be increased?

Yes, the rate of heat transfer between two iron blocks can be increased by increasing the temperature difference between the blocks, increasing the surface area of contact, decreasing the distance between the blocks, and using materials with higher thermal conductivity.

4. How is heat transferred between two iron blocks different from other materials?

Heat transfer between two iron blocks is different from other materials because iron has a high thermal conductivity, meaning it can transfer heat quickly and efficiently. Additionally, iron has a high melting point, allowing it to withstand high temperatures without melting.

5. What are some real-world applications of heat transfer between two iron blocks?

Heat transfer between two iron blocks is used in many industrial processes, such as welding, forging, and heat treatment. It is also used in household appliances, such as stovetops and irons, to transfer heat from a heating element to a metal surface for cooking or ironing.

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