Download U3f L3 4-17 Fluid Technology 3

March 9, 2010
DRILL
1. Get with a reliable partner and go over last night’s
homework together – Fluid Worksheet
2. We will be going over the homework in 8 minutes.
U3f – L3
Homework Review - #1
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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.
U3f – L3
Homework Review - #2
Examples of Fluid Technology:
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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
(Pressure = Force / Area)
PV = k
(Pressure x Volume = Constant)
P1V1 = P2V2
(Initial P x Initial V = Final P x Final V)
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
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
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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:
U3f – L3
Boyle’s Law
Problem (copy this problem):
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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 = F1 / A1
P2 = F2 / A2
P1 = P2
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
P2 = F2 / A2
F2 = P2 x A2
F2 = 20 psi x 1 in2 = 20 lbs.
U3f – L3
Problems
What is the mechanical advantage of this system?
MA = L / F
MA = (20 lbs)/ (10 lbs)
P1 = 20 psi
P2 = 20 psi
F1 = 10 lbs
F2 = 20 lbs
A1 = 0.5 in2
A2 = 1 in2
MA = 2
U3f – L3
Study for the Quiz tomorrow
U3f – L3