Heat and the First Law of Thermodynamics

In summary, the conversation discusses the use of Joule's apparatus to determine the increase in temperature of water after two masses fall through a distance of 3.50 m. The calculated work done in Joules is not equal to the change in temperature, but it is proportional to it with the relationship W = c m \Delta T, where c is the specific heat of water and m is the mass of the water.
  • #1
cmilho10
20
0
Consider Joule's apparatus described in Figure 20.1. Each of the two masses is 1.50 kg, and the tank is filled with 190 g of water. What is the increase in the temperature of the water after the masses fall through a distance of 3.50 m?

For this I know that PE=W, and that 2mgh is proportional to the change in temperature, but for some reason I can't get the correct answer

2(1.5 g)(9.8 m/s2)(3.5m)=103 C, but this is not correct
 
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  • #2
What you calculated is the work done in Joules, not the change in temperature. But the temperature change is proportional to the work done, but proportional does not mean equal. The relationship is as follows:
[tex]W = c m \Delta T[/tex]

Where c is the specific heat of water (look it up) and m is the mass of the water.
 
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1. What is heat?

Heat is the transfer of energy from one object to another due to a temperature difference between them. It is a form of energy that can be measured in joules or calories.

2. What is the First Law of Thermodynamics?

The First Law of Thermodynamics, also known as the Law of Conservation of Energy, states that energy can neither be created nor destroyed, only transferred or converted from one form to another. In other words, the total energy in a closed system remains constant.

3. How is heat related to the First Law of Thermodynamics?

Heat is a form of energy and therefore, it follows the First Law of Thermodynamics. This means that the energy input into a system in the form of heat must be equal to the amount of work done by the system, plus any change in internal energy.

4. What are some examples of the First Law of Thermodynamics in everyday life?

The First Law of Thermodynamics can be seen in a variety of everyday processes, such as the heating of a room with a heater, the cooling of a drink in a refrigerator, or the functioning of a car engine. In all of these processes, energy is transferred and converted from one form to another, but the total energy remains constant.

5. How is the First Law of Thermodynamics applied in scientific research?

The First Law of Thermodynamics is a fundamental principle that is applied in various fields of science, including chemistry, physics, and engineering. It is used to understand and predict the behavior of systems and their energy transfer processes. It also serves as a basis for the development of new technologies and energy-efficient systems.

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