The internal energy of a system is initially 27 J. A total of 33 J of energy is added to the system by heat...

1. The internal energy of a system is initially 27 J. A total of 33 J of energy is added to the system by heat while the system does 26 J of work. What is the system's final internal energy?

here are the equations we can use:
(-m1)(C1)(ΔT1)=(m2)(C2)(ΔT2)
Q=mcΔT
Q=mL
ΔU=Q-W
W=PΔV
There might be others I am forgetting...sorry

Please indicate which equation you use and why you used it. Thanks!

Use The 1st law of thermodinamic :

ΔU = Q - W ---> Q = 33 J
W = 26 J

ΔU = Uf - Ui

Uf - Ui = Q - W
Uf - 27 = 33 - 26

--> Uf = 7 + 27 = 34 J

you add 33 J and take away 26J, for a net gain of 7J, so the final energy is 7+27 = 34 J

I didn't use any of your equations, just addition and subtraction.

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