Which equation best expresses the first law of thermodynamics, assuming q is heat, u is internal energy, and w is work?

a.δw= δq+ δu

b.δw= δu − δq

c.δq= δu+w

d.δu=q −w

The first law of thermodynamics is expresses by

D. ΔU=Q-W

which means change in internal energy of system = Heat added to system minus work done by the system

All are expressed in Joules.

This law is based on principle of conservation of energy.

(d) is the correct option ''''

Explanation:

The first law of thermodynamics states the law of conservation of energy i. e. heat energy can neither be created nor be destroyed. The mathematical expression that show the first law of thermodynamics is as follows:

Where

is the change in internal energy

Q is the amount if heat added to the system

W is the work done by the system

Hence, the correct option is (d)