# Work done during expansion of a gas

• tanzerino
In summary, the conversation discusses the calculation of internal energy using the formula Eint=Q+W. The speaker notes that Q is smaller than the area under the curve, leading to a negative value for internal energy. However, when they try to calculate the work done using the graph, they get a much larger value, resulting in a negative answer. The other person suggests showing their work and confirms that they also get a negative answer. The conversation ends with the speaker expressing frustration with mistakes in their cengage material.
tanzerino
[PLAIN]http://img101.imageshack.us/img101/8176/24851738.png

it is definetaly negative as Eint=Q+W
and Q is smaller than the area under curve taking care of the scaling of pressure in atm.
but what i get is -1.5x10^6

Last edited by a moderator:
Einternal=Q+W
Q he said is given so +ve and work from the graph is -ve
calculated work was much greateer that's why i think the answer is -ve then wen i tried the numbers i get -1.5 which isn't an answer

any help?

You should show your work. But I get the same answer as you do.

$$\Delta Q = \Delta U + W$$

where W is the work done by the gas.

That work is the area under the graph. There appears to be an increase in volume of 5 m^3 and a drop in pressure from 7 to 3 atm. So the work done is (7+3)*5/2 = 25 atm-m^3 of work = 2.525e6 Joules.

So:

$$\Delta U = \Delta Q - W = 1.02e6 - 2.525e6 = -1.5e6 J$$

AM

thanks for your help.i will check for any mistakes with the teacher this is cengage and the second mistake already.shame!

## What is work done during expansion of a gas?

Work done during expansion of a gas refers to the energy that is required to move the gas against an external force, such as a piston, as it expands in volume.

## How is work done during expansion of a gas calculated?

The work done during expansion of a gas can be calculated using the equation W = PΔV, where W is the work done, P is the external pressure, and ΔV is the change in volume of the gas.

## What is the relationship between work done and expansion of a gas?

The work done during expansion of a gas is directly proportional to the change in volume of the gas. This means that as the gas expands, the work done also increases.

## What factors affect the work done during expansion of a gas?

The work done during expansion of a gas is affected by the magnitude of the external pressure, the change in volume of the gas, and the type of gas being expanded.

## What is the significance of work done during expansion of a gas?

The work done during expansion of a gas is important in understanding the thermodynamics of gases and their behavior. It is also crucial in various industrial processes, such as in the design of engines and turbines.

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