FL: Forms of the First Law

Forms of the First Law of Thermodynamics

$\Delta U + \Delta E_{k} + \Delta E_{p} = W + Q $

$\Delta u + \Delta e_{k} + \Delta e_{p} = w + q $

$ dU + dE_{k} + dE_{p} = \delta W + \delta Q $

$du + de_{k} + de_{p} = \delta w + \delta q $

$ \frac{dU}{dt} + \frac{dE_{k}}{dt} + \frac{dE_{p}}{dt} = \dot W + \dot Q $

$\frac{du}{dt} + \frac{de_{k}}{dt} + \frac{de_{p}}{dt} = \dot w + \dot q $


Write the integral and differential forms of the first law


Describe the physical meaning of each of the terms within both the integral and differential form of the first law


Determine when each term in the first law is zero or negligible


We will often ignore changes in potential and kinetic energy. Why?


If we assume that the stone from the previous example problem lands in a puddle of water (10kg) at the bottom of the mine shaft, and that the energy lost by the stone s completely used to heat the water. What is the final temperature of the water if it started at $20^\circ$C?