1 / 5

Solids and Fluids

Solids and Fluids. Summary. Elastic deformation of solids – Basic concept: . Stress = Force per unit area , causes the deformation Strain = Measure of the deformation Elastic modulus = The larger it is the harder to deform . We’ve seen three different types of deformation: .

emery
Download Presentation

Solids and Fluids

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Solids and Fluids Summary PHY231

  2. Elastic deformation of solids – Basic concept: Stress = Force per unit area , causes the deformation Strain = Measure of the deformation Elastic modulus = The larger it is the harder to deform • We’ve seen three different types of deformation: • Young’s modulus (Y): Elasticity in length • Shear modulus (S): Elasticity of shape • Bulk modulus (B): Elasticity of Volume

  3. Density = Mass / Volume • Density of an object: • Pressure : (from force perpendicular to surface) Pressure = Force / Area Pressure in Pa = N/m2 • Pressure in a static fluid Pressure increases with depth. If location 2 is deeper by a height h compare to a higher location 1 in the fluid, one has: Open tube manometer Measure P of the fluid Barometer Measure atm. pressure Gauge pressure = P-P0

  4. Pascal’s principle • Application: • Lifting of heavy objects using small forces Change in pressure is transmitted everywhere in an enclosed fluid Pressure transmitted to the right • Buoyant force B (supportive force from a fluid) Add pressure on the left A small force F1 creates a large force F2 because area A1 is much smaller than area A2 (same pressure F1/A1=F2/A2) Enclosed fluid Buoyant force is equal to the weight mfg of the fluid displaced by the object • Object denser than the fluid sinks • - Object less dense than the fluid floats: • - To float, the object must displace a mass of fluid equals to its own mass

  5. Flow rate: How much volume of fluid is transported every second in the fluid • Equations for incompressible and non-viscous fluid in motion: Continuity equation: Typically, fluid flowing in a pipe. If the cross-section of the pipe changes from A1 to A2, the velocity of the fluid must change. Pipe gets smaller, velocity increases. Bernouilli’s equation: At two different locations in the fluid. Comes from energy conservation. P is the static pressure seen before. v is the velocity of the fluid and y the height. Typically when fluid speeds up the static pressure decreases. • For viscous fluids, use Poiseuille’s law: Flow rate depends very strongly on the radius R of the pipe it is flowing through. Flow rate increases also with pressure drop DP and decreases for larger fluid viscosity h and larger pipe length L

More Related