Thermodynamics- 1st Law Question

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A gas in a piston is heated, maintaining a constant pressure of 8 kPa, while the piston moves outward by 40 mm, with a heat input of 42 J. The first law of thermodynamics is applied, specifically the equation Q - W = ΔU, where Q is heat added, W is work done by the gas, and ΔU is the change in internal energy. The user initially struggles to calculate work but is advised that only the change in volume is necessary, which can be determined from the cross-sectional area and displacement. The user successfully resolves the problem shortly after receiving assistance. The discussion highlights the application of the first law of thermodynamics in a practical scenario.
FordRanger4x4
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Homework Statement



A gas is enclosed in a container fitted with a piston of cross-sectional area 0.1 m2. The pressure of the gas is maintained constant at 8 kPa, while the gas is heated slowly and the piston moves outward a distance of 40 mm. Heat input to the gas during this process is 42 J. What is the increase in internal energy of the gas?

Homework Equations



I know that the first law needs to be used here, and i am neglecting Kinetic and Potential Energy

Q-W=(delta)U

The Attempt at a Solution



Im having trouble solving for work, this is what i have so far.

42J-8KPa(V2-V1)=(delta) U

any help would be great, thanks

FordRanger
 
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You don't really need to know V1 and V2. You only need the change in volume. Since you have the cross sectional area of the cylinder and the displacement, you can find delta-V and complete your problem.
 
Thanks, i ended up figuring it out pretty soon after posting.
 

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