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U3f – L3 1. Take out your homework problem worksheet so that we can go over it now. March 17, 2010 DRILL

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U3f – L3 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 - #1

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U3f – L3 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 Examples of Fluid Technology: Homework Review - #2

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P = F / A (Pressure = Force / Area) PV = k (Pressure x Volume = Constant) P 1 V 1 = P 2 V 2 (Initial P x Initial V = Final P x Final V) Homework Review - #3 U3f – L3

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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? Homework Review - #4 Step 1: Write given information P1 = 80 psi V1 = 6 L P2 = ? V2 = 10 L Step 2: Write the formula and solve P 1 V 1 = P 2 V 2 (80 psi) x (6 L) = P2 x (10 L) 480 psi*L = P2 x (10 L) 10 L 10 L P2 = 48 psi

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U3f – L3 A sample of hydrogen gas is compressed from 300 cm 3 to 2.5 cm 3. Its pressure is now 5 psi. What was the original pressure of the helium? Homework Review - #5 Step 1: Write given information P1 = ? V1 = 300 cm 3 P2 = 5 psi V2 = 2.5 cm 3 Step 2: Write the formula and solve P 1 V 1 = P 2 V 2 P1 x (300 cm 3 ) = 5 psi x (2.5 cm 3 ) P1 x (300 cm 3 ) = 12.5 psi* cm 3 300 cm 3 300 cm 3 P2 = 0.0417 psi

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U3f – L3 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: Fluid Systems

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U3f – L3 Problem (copy this problem): 1.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? P 1 = P 2 Boyle’s Law P1 = F1 / A1P2 = F2 / A2

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U3f – L3 Problems Solution: Step 1: Write given informationP1 = ? F1 = 10 lbs.F2 = ? A1 = 0.5 in 2 A2 = 1 in 2 Step 2: Write the formula and solve for the unknowns P1 = F1 / A1 P1 = (10 lbs) / (0.5 in 2 ) P1 = 20 psi P1 = P2 = 20 psi F2 = 20 psi x 1 in 2 = 20 lbs. P2 = F2 / A2 F2 = P2 x A2

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

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Complete the fluid technology problem sheet. U3f – L3

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