And We're Back...

And everyone is just overjoyed about that fact...

Physics A and B have been working on describing fluids in terms of pressure changes with position in a fluid and how fluids in motion demonstrate conservation of mass. Building on the lab work conducted before break, folks generated the formula for calculating fluid pressure at any position in a fluid column and yesterday we discussed how those pressure differences arise and how they, in turn, give rise to buoyant forces. The fluids we discussed, however, were still fluids. When fluids are set in motion, the model is more complicated, though we do simplify things by working under the ideal-fluid model for our fluid-flow analyses. We discussed the properties of idea fluids and ventured into how fluids in motion demonstrate conservation of energy. In a closed fluid system, the flow rate remains constant, whether reported in mass/time or volume/time. For idea fluids, the density remains constant, so either of those two reporting units (kg/s or m³/s) document that the amount of fluid moving through a pipe remains constant. Since the produce of area (m²) and velocity (m/s) result in the unit of m³/s, that formula is useful for calculating flow rate. Therefore Av is constant or Av = Av for any two sections of pipe. Tomorrow, we'll add pressure to the mix with Bernoulli's principle.

Intro Physics have been examining the law of conservation of energy. In yesterday's lab, conversions between kinetic/gravitational potential and kinetic/elastic potential were examined to show that patters of energy change of one type were matched by energy changes in the other type to keep the total energy in the system constant. Today, we added some math to that relationship and saw how conservation of energy can be useful for problem solving where kinematics may give us a headache. Tomorrow, we'll look at why, even though conservation of total energy is inviolate, conservation of mechanical energy isn't.

Honors Physics started their quick unit on thermodynamics. Work for a thermodynamics system was defined as the product of pressure and volume change. No volume change, no work done on or by a gas. We assigned sign conventions to work and defined specific thermodynamic processes. Today, time was taken to look more closely at those processes in terms of internal energy change, work and heat and how cyclic processes fit into the picture, using heat engines and refrigeration systems as examples.