Quick question about the heat Q transferred between water and skin

They want the heat transferred from the water to the skin, not gained by the water. So the sign should be reversed, and your answer should be positive. In summary, the correct calculation for the heat transferred from the water to the skin is Q= 0.025 * 4190 * (100-34) = 6910. This is because the initial temperature is 100∘C and the final temperature is 34∘C, resulting in a positive value for the heat transfer.
  • #1
bluesteels
28
1
Homework Statement
How much heat Q1 is transferred by 25.0 g of water onto the skin? To compare this to the result in the previous part, continue to assume that the skin temperature does not change.

Assume that water and steam, initially at 100∘C, are cooled down to skin temperature, 34∘C, when they come in contact with your skin
Relevant Equations
Q=mc delta
c = 4190
My work

Q= 0.025 * 4190 * (34-100) = -6910

but on chegg but did they do

Q= 0.025 * 4190 * (100-34) = 6910. I thought the initial is 100C and final is 34 because it goes from 100 to 34
 
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  • #2
bluesteels said:
Homework Statement:: How much heat Q1 is transferred by 25.0 g of water onto the skin? To compare this to the result in the previous part, continue to assume that the skin temperature does not change.

Assume that water and steam, initially at 100∘C, are cooled down to skin temperature, 34∘C, when they come in contact with your skin
Relevant Equations:: Q=mc delta
c = 4190

My work

Q= 0.025 * 4190 * (34-100) = -6910

but on chegg but did they do

Q= 0.025 * 4190 * (100-34) = 6910. I thought the initial is 100C and final is 34 because it goes from 100 to 34
You did the correct calculation, final minus initial, for the heat gained by the water, which is negative. That is not what the question asks for.
 
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1. How does the temperature of the water affect the amount of heat transferred to the skin?

The temperature of the water has a direct impact on the amount of heat transferred to the skin. The higher the temperature of the water, the more heat will be transferred to the skin. This is because heat always flows from a hotter object to a cooler object.

2. Does the surface area of contact between the water and skin affect the heat transfer?

Yes, the surface area of contact plays a significant role in the amount of heat transferred between water and skin. A larger surface area allows for more heat to be transferred, while a smaller surface area will result in less heat transfer.

3. How does the duration of contact between water and skin impact the heat transfer?

The longer the duration of contact between water and skin, the more heat will be transferred. This is because the longer the objects are in contact, the more time there is for heat to transfer from the water to the skin.

4. Is the type of material of the container holding the water important in heat transfer?

Yes, the type of material of the container can affect heat transfer between water and skin. Materials that are good conductors of heat, such as metal, will transfer heat more efficiently than materials that are poor conductors, such as plastic.

5. How does the temperature of the skin affect the heat transfer from water?

The temperature of the skin also plays a role in heat transfer from water. If the skin is warmer than the water, heat will transfer from the skin to the water. If the skin is cooler than the water, heat will transfer from the water to the skin.

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