#### Derivation of a Pressure Field and Fluid at Rest: Summary

The answers to the ConcepTests are given below and will open in a separate window.

##### Key points from this module:

- By using a fluid element, the surface and body forces can be used to derive the equation of motion for a fluid with no shear stresses.
- If a fluid is at rest, pressure only changes in the z direction.

##### From studying this module, you should now be able to:

- Use a differential element to determine the equation of motion for fluid statics and dynamics.
- Apply Newton’s Second Law to a differential system.
- Derive the equation of motion for a fluid.

*Prepared by Janet deGrazia, Department of Chemical and Biological Engineering, University of Colorado Boulder*