Work at Constant Volume

[Minh-Anh Pham 1B]

Is work at constant volume always zero? If it is, is it because the volume of the system doesn't change, so the system does not do work on the surroundings and vice versa? As a follow up question, would the change in internal energy then equal just q?

[Madeline Redmond 2A]

Yes, when the volume is constant work=0. This is because w=-P*deltaV and when the change of volume is zero, the work must be equal to zero. And yes, when w=0, deltaU=qv, which indicates that the volume is constant.

[Ishika Gupta 3E]

Yes, it helps to think about the equations to conceptualize this. The work equation is w = -p*deltaV. If deltaV = 0, then work will also equal 0. The internal enegry equation is deltaU = q - w. If w = 0, then deltaU = q.

[Kelly Tang 1B]

Yes! Work is always zero at constant volume because work is done through expansion/compression, which means that if volume is zero, there is no expansion/compression being done. If work is zero, then the change in internal energy will just be q since the equation would be ΔU = q + w(0).

[Marina Nimnual]

Yes. ΔU=q+w, but since constant volume means that there is no change in volume, w=-PΔV will be 0 (work is not being done or by the system), which will just make it ΔU=q.

[Nikki Ma 3B]

Yep! work is equal to 0 if the volume is constant. this is because if we refer to the work equation there is a (delta) V which is [final volume - initial volume], but since volume is constant and not changing this factor equals zero and so the entire value of work is 0

[Matthew Do 2G]

Yes exactly that,

When looking at the equation for internal energy (deltaU= q + w), and work= P(detlaV), you can see that when the volume is constant throughout the system and no work will be done by or on the system and the w value will be eliminated from the internal energy equation. This leaves deltaU= q. I hope this helps !

[306025535]

Yes, at a constant volume the "deltaV" of a system is 0. When you put this value of 0 into the work function "w=-P(deltaV)", work=0. In regards to your follow up question, the delta U formula "deltaU= q +w" will just equal q since w=0.

[Leah Schlageter 1A]

Yes, work at a constant volume would be zero because there is no change via compression and expansion