Mid year review. Format Part 1: – Multiple Choice : 33 questions (4 points each) Part 2: – Short...
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Transcript of Mid year review. Format Part 1: – Multiple Choice : 33 questions (4 points each) Part 2: – Short...
Mid year review
Format
• Part 1:– Multiple Choice : • 33 questions (4 points each)
• Part 2:– Short Answer:• 15 questions (4 points each)
Topics
• Earth and Space– Lithosphere:• Ore vs. Mineral (1)
Lithosphere
Minerals vs. Ore
Mineral Ore
- $ $
Environmental Effects of mining
• Deforestation• Destruction of habitat
• Pollution• Heavy Machinery
Topics
• Material World:– Chemical Changes• Oxidation (1)• Combustion (4)
– Electricity• Charges (4)• Static Electricity (2)• Electricity formulas (9)• Circuit Design (5)
Changes
Changes (5)
• Combustion– Visible signs of rapid combustion– Fire triangle
• Oxidation– Identify an Oxidation reaction
Types of chemical changes
• Oxidation:– Definition:• Chemical change that occurs when a substance reacts
with oxygen (O2)
– Examples• Rusting• An apple turning brown
– Particle Model
Types of chemical changes
• Combustion:– Type of oxidation reaction that releases a large
amount of energy (light and heat)
– Examples• Fire
– Fire Triangle
• Combustion Triangle
Electricity
Elementary particles
• Protons Positive
• Electrons Negative
• Neutrons Neutral
What does this mean…
• An element with more electrons than protons will be considered negatively charged
• A substance with less electrons than protons will be considered positively charged
How do charges react?
• Opposites attract, Like charges repel
Practice Questions
A B B C C D
Practice Questions
If I say that by rubbing silk and glass together, the silk gains electrons.
Will silk be positively or negatively charged?
Static electricity
• 1. Friction
• 2. Conduction
• 3. Induction
Dynamic electricity
• What conducts electricity?– Metals– Graphite– Electrolytes (salts in water)
• Conductivity of a wire– A wire’s conductivity (how much electricity can
pass through in a given time) will
• Increase if the diameter of the wire increases• Increases if the length of the wire decreases• Increases if the temperature decreases• Change with substance used (copper is the best)
Which of the following
copper
copper
10 cm
10 cm A)
B)
25°C
100°C nichrome
10 cm
100°C
copper 10 cm
25°C C)
D)
plastic
Circuits
Circuits (5)
• Electrical functions• Series vs. parallel circuits • Draw a circuit• Connection of an ammeter and voltmeter• Identify the circuit based on description
Circuitry basics• All circuits must have elements that perform the
following electrical functions
– Power supply: Battery– Conductors: Wires– Transform energy: Resistors, Lights
• To that you can add– Control Switch– Protection Fuse
Circuitry Basics
Parallel– More than 1 pathway
– Independent
– Lights controlled separately
– More energy efficient
Series– Only 1 pathway
– Dependant: 1 goes out they all do
– 1 switch controls everything
– Less energy efficient
Drawing a circuit
• Read the question carefully– Find out whether they are asking for a series or
parallel circuit• Draw the circuit (1, 2 or 3 boxes)• Add the power supply• Add and label the necessary components
Adding Ammeter and Voltmeter• An Ammeter– Measures current intensity – Placed directly in the circuit
• A voltmeter– Measures potential difference– Measures 2 points
Questions on Circuits
• A circuit consists of two light bulbs (L1 and L2), a switch, and a power supply. When switch 1 is open L1 stays on and L2 goes out. Close the switch and both lights are on.
• Draw the circuit
VA)
VB)
C)
D)
V
V
A
R1 R 2 R1 R2
A
R1 R2
A
R1 R2
A
A)
B)
C)
D)
What are the electrical functions found in the following circuit?
Formulas
Formulas (9)• Basic Applications– V=RI– E=Pt– P=VI– Qualitative V=RI
• Dual Equations
• Find the most energy efficient appliance (calculate E)
To solve• Read the question carefully
• Underline the important information and highlight what is being asked of you (what should your final answer be)
• Find the formula that has your missing variable in it.
• Identify the remaining relevant information in your question. (If you are missing a second variable you need a second formula)
• Solve the problem
• Do not forget to include your units
• Calculate the resistance value for each of the following resistors
• Resistor– A 2 V 10 A– B 5 V 3A– C 3 V 20A– D 6 V 2A
Question– While having breakfast, you notice the following
information on the specification plate of the toaster.
– You also note that this toaster toasts the bread in 1.5 minutes. What quantity of electrical energy is consumed by the toaster's element to toast the bread?
120 V6 A
60 Hz
Topics• Technological World
– Motion transmission and transformation systems (1)– Speed change and torque (3)– Adhesion and friction (1)– Drawing in Multiview (1)– Drawing developments (1)– Tolerances (2)– Electrical functions (5)– Controls (1)– Resistance coding (3)– Constraints and Properties (2)– How something works (2)
Motion System
Transmission and transformation
Motion Systems
Motion Transmission• Same type of motion
• Gear Train• Chain and Sprocket• Worm and Worm gear• Friction gear• Belt and pulley
Motion Transformation• Different types of motion
• Rack and Pinion• Cam and Follower• Screw gear systems• Slider and Crank
Speed Change
• Speed ratio: driver gear driven gear
Adhesion and Friction
• Adhesion:– when two objects want to stick together– Better adhesion when:• Objects have rough surfaces• Objects are warmer• No lubricants
• Friction: force that opposes motion
TECHNICAL DRAWINGS
Different Views
Multiview• A set of 2D drawings• Uses normal graph paper• Uses all types of lines
Isometric• A single 3D drawing• Uses weird dotted paper• Uses only visible lines
Developments
Tolerance
Tolerance Dimensioning
• Tolerance is the total amount that a specific dimension is permitted to vary;
• It is the difference between the maximum and the minimum limits for the dimension.
• For Example a dimension given as 1.625 ± .002 means that the manufactured part may be 1.627” or 1.623”, or anywhere between these limit dimensions.
Allowance & Clearance
Interchangeable Fit
Electronics
Electrical Functions
• 1. Power supply: – Supplies energy to the circuit– Examples: Battery, power supply, photovoltaic cell
• 2. Conduction:– Ability to transfer electrons
Factors that affect conduction
• Length:– The shorter the wire the better the conductor
• Diameter– The wider the wire the better the conductor
• Temperature– The colder the wire the better the conductor
• Nature of the material– A metal is better than a metalloid (carbon) which is
better than a non-metal
• 3. Protection:– Element whose goal is to protect the circuit in
case of a surcharge
Electrical functions continued
• 4. Insulation: – Element whose function is to slow down the
electrical current
p.468
Electrical Functions
• 5. Control– Component that has the ability to control the flow
of electricity in a circuit
– Flip flop switch, lever switch, push button, magnetic switch
Defining switches
• UniPolar vs. Bipolar • Unidirectional vs Bidirectional
Electrical Functions
• 6. Transformation of energy– Any component that has the ability to transform
electrical energy into another form of energy (heat, light, magnetism, vibration)
• 7. Relay– Function: Element that uses a small amount of
power to switch another circuit which requires a larger amount of power
• 8. Condenser (Capacitor)– Function: Stores energy• Allows to even out current fluctuations• Allows to discharge stored energy in one shot (e.g.
camera flash)
• 9. Diode– Allows the current to flow in only one direction• Has low resistance one way, incredibly high resistance
the other)• Converts Alernating current into direct current
• 10. Transistor– Function: Amplifies an electronic signal– Used in computers – binary code
Materials
Properties
• Hardness• Resilience• Malleability• Ductility• Stiffness• Conductor of heat• Conductor of electricity• Resists corrosion
Properties
• Hardness• Resilience• Malleability• Ductility• Stiffness• Conductor of heat• Conductor of electricity• Resists corrosion
Wood
Properties
• Hardness• Resilience• Malleability• Ductility• Stiffness• Conductor of heat• Conductor of electricity• Resists corrosion
Ceramic
Properties
• Hardness• Resilience• Malleability• Ductility• Stiffness• Conductor of heat• Conductor of electricity• Resists corrosion
Metal