Physics Lect 5

The flashcards below were created by user laskiru on FreezingBlue Flashcards.

1. Density
• ρ = m / V
• m: mass
• V: volume
• * remember that density changes with compression because volume will change
2. Specific Gravity
• Makes density more intuitive
• SG = ρsubstance / ρwater
• ρwater: 1 g/cm3 or 1000 kg/m3
3. Pressure
• P = F / A
• when an object is submerged: pressure is equal to the force felt on the object divided by the surface area
• * remember that pressure is there regardless of if the object is, this just makes it more intuitive
4. Fluids at Rest
• Fluids are at rest when they are only experiencing a force perpendicular to its surface
• P = ρgy
• * remember that if the container is open you must add Patmos which is 101 000 Pa
5. Pascal's Principal
• Pressure applied to an incompressable fluid will be evenly distributed
• a hydrolic lift utilizes this principal (F applied to smaller S.A. --> P trans --> since the larger S.A. is larger the F is greater on it (no change in work though so the distance is less)
6. Archimedes Principal
• an object submerged in water displaces a volume of fluid equal to its own volume
• an object floating displaces a volume of fluid equal to its weight
7. Buoyancy Force
• Submerged: Fb = ρfluid V g
• Floating: Fb = mgobj = mgfluid
• Fraction Submerged: ρobj / ρfluid
8. Center of Buoyancy
• is the point were the center of mass would be if the object were uniformly dense
• the actual center of the object
9. Fluids in Motion - Types of Motion
• 1) Random Translational - contributes to fluid pressure as in a fluid at rest
• 2) Uniform Translational - shared by molecules at a given location
• energy from these two types of motion can be converted back and forth
10. How do real fluids compare to ideal fluids?
• real have drag, viscocity
• drag works at the fluid-object interface, therefore the greatest velocity will be at the point farthest from that interface
11. Flow Rate
• Q = A v
• Q: volume flow rate
• A: area
• v: velocity
12. Bernoulli's Equation
• P + ρgh + 0.5ρv2 = K
• the sum of these three terms is a constant at any point in the fluid
• term 1: pressure
• term 2: potential
• term 3: kinetic
13. As velocity increases, pressure
• decreases
• think of the bee swarm standing vs. running analogy
14. Surface Tension
• temp dependent - the higher the temp the weaker the surface tension
• if the adhesive forces (to the container) are stronger than the cohesive forces (between molecules) the miniscus will be a 'U' shape
15. Solids and Heat
Typically expand when heated
 Author: laskiru ID: 58894 Card Set: Physics Lect 5 Updated: 2011-01-10 03:21:24 Tags: Fluids Solids Folders: Description: Fluids and Solids Show Answers: