Physics Lab Question - High School

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Homework Help Overview

The discussion revolves around a high school physics lab focused on specific heat, where students heated metals and placed them in cool water to observe temperature changes. A question raised concerns the reasoning behind starting the water temperature below room temperature.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants inquire about the final temperature of the water after adding the metal and its relation to room temperature. There is a discussion about the implications of starting with water below room temperature and how it affects heat exchange with the surroundings.

Discussion Status

Some participants have provided insights into the reasoning behind the initial water temperature, suggesting that starting below room temperature minimizes heat loss to the environment, thus potentially leading to more accurate measurements. There is acknowledgment of the balance needed between heat gain from the surroundings and heat loss as the water warms.

Contextual Notes

Participants are exploring the effects of initial water temperature on the accuracy of specific heat measurements, with some assumptions about heat exchange dynamics being questioned.

PlanetLazy
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In my introductory physics class in high school we did a lab on specific heat. We heated metals and placed them into cool water and observed the temperature change to find the specific heat of the metal. One of the questions on the lab puzzled me.
- Why was the cool water purposely started well below room temperature?
What is the reason for having the water below room temperature?
 
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What was the final temperature of water after adding the metal piece? Was it above room temperature?

ehild
 
ehild said:
What was the final temperature of water after adding the metal piece? Was it above room temperature?

ehild

it was between 26 - 30 degrees celsius which is a little above room temperature.
 
The water exchanges some heat with the surroundings. If the water is initially at room temperature, it losses heat all the time during the metal warms it up. That causes error in the final temperature.

If you start below room temperature, the water gets heat from the surroundings first, and when it warms above room temperature, it losses heat. The gain and loss about cancel each other.
The best is when you find a balance, so as the room temperature is halfway between the initial and final temperature of water.

ehild
 
thank you very much and great explanation!
 

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