# Thermal Kinetic Physics Question involving PV diagram

• KaseyKC
In summary, the student is struggling with a question A4 and is unable to obtain solutions from their university. They have a resit exam coming up and are trying to understand the equation dU=dQ-PdV, where internal energy equals heat flow plus work done. They receive clarification that the heat added to the system plus the work done on the system equals the change in internal energy.
KaseyKC

## Homework Statement

I'm stuck on question A4 that is linked below. University won't provide me with any solutions. I have a TKP resit exam next month.

dU=dQ-PdV

## The Attempt at a Solution

Internal energy is equal to heat flow plus the work done. Work done is 0 because it's isochoric. So Internal energy is equal to the heat flow right? 20J.

#### Attachments

• TKP exam 2014.pdf
308.8 KB · Views: 303
Hello, KaseyKC. Welcome to PF!

Be careful with how you word your answer. The heat added to the system plus the work done on the system equals the change in internal energy of the system.

KaseyKC

## 1. What is a PV diagram?

A PV diagram is a graphical representation of the pressure-volume relationship in a thermodynamic system. It shows the changes in pressure and volume as the system undergoes a process.

## 2. How do you interpret a PV diagram?

The x-axis of a PV diagram represents volume and the y-axis represents pressure. The area under the curve on the diagram represents the work done by or on the system. The slope of the line on the diagram represents the change in pressure over the change in volume.

## 3. What is the significance of the shape of a PV diagram?

The shape of a PV diagram can indicate the type of process a system is undergoing. For example, a horizontal line indicates a constant pressure process, while a vertical line indicates a constant volume process. A curved line indicates a non-ideal process with changing pressure and volume.

## 4. How is the first law of thermodynamics related to a PV diagram?

The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or converted. In a PV diagram, the work done by or on the system is represented by the area under the curve, which is a visual representation of energy transfer.

## 5. What factors can affect the shape of a PV diagram?

The shape of a PV diagram can be affected by various factors such as the type of gas, the initial and final states of the system, and the efficiency of the process. Additionally, changes in temperature, pressure, and volume can also impact the shape of a PV diagram.

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