a system udergoes a process consisting of the following 2 steps-
1. absorbs 79J of heat while 26J of work is done to it
2. system absorbs 26J of heat while preforming 79J of work
what is overall ÄE?
is it 52J?
I think you are correct but get a second opinion.
Step 1: Change in E2 = q+w ; 79+26=105J
Step 2: Change in E2 = 26-79=-53J
Change in E overall = Change in E1 + Change in E2 ; 105-53=52J
So yes, you are correct.
To determine the overall change in energy (ΔE) of the system, we need to consider the first and second steps separately and then add up the changes.
In the first step, the system absorbs 79J of heat (q1) while 26J of work (w1) is done to it. The initial change in energy for this step can be calculated as follows:
ΔE1 = q1 + w1
= 79J + (-26J)
= 53J
Note that the work done value is negative since it is work done to the system (done by an external agent).
In the second step, the system absorbs 26J of heat (q2) while performing 79J of work (w2). The initial change in energy for this step can be calculated as follows:
ΔE2 = q2 + w2
= 26J + (-79J)
= -53J
Again, the work done value is negative since it is work done by the system.
To determine the overall change in energy (ΔE) of the system, we add up the changes from both steps:
ΔE = ΔE1 + ΔE2
= 53J + (-53J)
= 0J
Therefore, the overall change in energy (ΔE) is 0J, not 52J as you suggested.