U3f – L3 April 17, 2008 DRILL Get with a reliable partner and go over last night’s homework together (numbers 1-5 on front of worksheet). We will be going over the homework in 8 minutes.

U3f – L3 Homework Review - #1 Technology – the application of knowledge, tools, and skills to solve problems and extend human capabilities. Technology System – a group of subsystems working together to solve problems and extend human capabilities. Core Technologies – several engineering resources that are the “building blocks” of all technology systems. Volume – how much space an object occupies Force – a push or pull Pressure – a force applied over an area Closed System – a system in which no fluid can enter or leave. Open System – a system in which a fluid can enter or leave. Fluid – a substance (as a liquid or a gas) that conforms to the outline of its container Fluid Technology – the technology of using fluid, either gas (pneumatics) or liquid (hydraulic), to apply force or to transport.

Homework Review - #2 Examples of Fluid Technology: U3f – L3 Homework Review - #2 Examples of Fluid Technology: Air brakes on a truck Tires on a car Airfoils on an airplane Warm-air heating ducts Hydraulic jack Plumbing in a school Hydro-electric dam Fuel pipelines Streamlined surfaces of airplanes for efficient air flight Rough surfaces of golf balls for efficient flight Aerodynamic vehicle design for improved gas mileage

U3f – L3 Homework Review - #3 P = F / A PV = k P1V1 = P2V2

Homework Review - #4 P1V1 = P2V2 (80 psi) x (6 L) = P2 x (10 L) U3f – L3 Homework Review - #4 A gas system has initial pressure and volume of 80 psi and 6 L. If the volume changes to 10 L, what will the resultant pressure be in psi? Step 1: Write given information P1 = 80 psi V1 = 6 L P2 = ? V2 = 10 L Step 2: Write the formula and solve P1V1 = P2V2 (80 psi) x (6 L) = P2 x (10 L) 480 psi*L = P2 x (10 L) 10 L 10 L P2 = 48 psi

Homework Review - #5 P1V1 = P2V2 P1 x (300 cm3) = 5 psi x (2.5 cm3) U3f – L3 Homework Review - #5 A sample of hydrogen gas is compressed from 300 cm3 to 2.5 cm3. Its pressure is now 5 psi. What was the original pressure of the helium? Step 1: Write given information P1 = ? V1 = 300 cm3 P2 = 5 psi V2 = 2.5 cm3 Step 2: Write the formula and solve P1V1 = P2V2 P1 x (300 cm3) = 5 psi x (2.5 cm3) P1 x (300 cm3) = 12.5 psi*cm3 300 cm3 300 cm3 P2 = 0.0417 psi

U3f – L3 Fluid Systems Open System - a system in which a fluid can enter or leave - Irrigation systems, forced hot air, engines, etc. Closed System - a system in which no fluid can enter or leave. - Radiator heating/cooling, hydroponics, etc. Valve – a mechanical device that starts, stops, or regulates the flow of a fluid. Meter – an instrument for measuring the quantity of water passing through a particular outlet. Resistance to flow:

Problem (copy this problem): U3f – L3 Boyle’s Law Problem (copy this problem): The diagram below illustrates how hydraulic brakes in a car work. The pedal must be pressed with a force of 10 lbs. The surface area of the piston connected to the pedal is .5 square inch. If the surface area of the piston connected to the other end of the brake line is 1 square inch, what is the force applied to that piston? P1 = P2 P1 = F1 / A1 P2 = F2 / A2

Solution: Problems Step 1: Write given information P1 = ? P1 = ? U3f – L3 Problems Solution: Step 1: Write given information P1 = ? P1 = ? F1 = 10 lbs. F2 = ? A1 = 0.5 in2 A2 = 1 in2 Step 2: Write the formula and solve for the unknowns P1 = F1 / A1 P1 = (10 lbs) / (0.5 in2) P1 = 20 psi P1 = P2 = 20 psi F2 = 20 psi x 1 in2 = 20 lbs. P2 = F2 / A2 F2 = P2 x A2

Problems What is the mechanical advantage of this system? MA = L / F U3f – L3 Problems What is the mechanical advantage of this system? MA = L / F MA = (20 lbs)/ (10 lbs) MA = 2 P1 = 20 psi F1 = 10 lbs A1 = 0.5 in2 P2 = 20 psi F2 = 20 lbs A2 = 1 in2

Complete the fluid technology problem sheet. U3f – L3 HOMEWORK Complete the fluid technology problem sheet.