Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Grade 9 Tech. Module Unit 2-Basic skills
Introduction • Topic 1: Energy Conversion • Topic 2: Measuring Energy • Topic 3: Schematics and Pictorials • Topic 4: Fabrication
Measuring Mass Mass is a measure of the amount of matter in an object and is measured in kilograms (Kg). The mass of an object can be determined using an equal arm balance. Activity - Measure the mass of the provided objects. Record the results in a table
Measuring Force Force is the measurement of influences that change the direction of an object. Force can be measured using a spring scale calibrated in Newtons.
Measuring Force • Activity • Measure the weight of an object using a spring scale. • Measure the force required to pull the object across a surface. • Record the results in your table • - Describe how the mass of an object and the force required to lift the object or drag it across a surface are related.
Measuring Mass • Activity • Measure the mass of the provided objects. • Record the results in a table
Calculating Work Work occurs when energy gets transferred from one object to another object. The mathematical relationship is: W=F×d A few points: • The mass has to move for work to be done on the object. • The mass has to move in the direction of the applied force. • Weight is equivalent to force of gravity. • The spring scale should be parallel to the surface when pulling the object across the table.
Calculating Work W=F×d(measured in N.m or Joules) Activity Part A Determine the work done in pulling an object across a horizontal surface. - Measure the force to pull the object (F) - Measure the distance you pulled the object.
Calculating Work W=F×d(measured in N.m or Joules) Part B Calculate the work done when the mass is lifted through a distance - Measure the force to lift the object (F) - Measure the distance you lifted the object.
Example 1: How much work is done by a person who uses a force of 30 N to move a grocery buggy 5 m? Given: F = 30 N d = 5 m W = ? Solution: Use W = F x d W = F x d = 30 N x 5 m AnswerW = 150 J
Example 2: • 55, 000J of work is done to move a rock 25m. How much force was applied? • Given • W=55,000 J • d=25m • F=? • In this problem, we are looking for force, so the equation must be rearranged. • EquationF = W = 55,000J = ? • d 25m • AnswerF = 2200J • Handout: Practice exercise - work
Measuring Electricity Voltage (V) is the difference in electric potential or the total charge between the two terminals. Current (I) is the rate at which the electric charges move through the conductor.
Measuring Electricity Power(P)is the rate at which work gets done. In the case of electricity, we say that electrical power is the rate at which electrical energy is transferred by an electric circuit. Electrical Energy (E) is the scientific form of electricity, and refers to the flow of power or the flow of charges along a conductor to create energy.
Calculating Electrical Power Electrical power (P) is defined as: Electrical Power = Voltage x Current or, substituting the symbols P = VxI (watts) Activity Use a multimeter to measure the current and the voltage being used by a small bulb . Calculate the power of the bulb.
Calculating Energy The mathematical relationship is: Energy = (current × voltage) × time Energy = VItor E = Pt (Joules) Activity Use a multimeter to measure the current and the voltage being used by a small bulb over a given time. Calculate the energy used by the bulb.
Measuring Electricity: Exercise Example 1: You have an electric heater in your room. If it operates at 220 volts and consumes 10 amps of electricity, what is its power rating? Given: V = 220V I = 10A P = ? Solution: Use the formula, P = IV P = VI P = 220V x 10A P = 2200W (W is the same as watts)
Example 2: How much electrical energy (E) is consumed by a 2200 W electric heater if it is turned on for 12 hours? Cost = kilowatt x hours x cost/kwh Given: P = 2200 W = 2.200 kilowatts = 2.20 kw T = 10 hrs Cost/ kwh = $0.10 Cost = 2.20 kw x 10 h x $0.10/kwh = $ 2.20 E = P x t E= 2200 W x 43200 sec = 95,040,000 W-s or 95,040,000 Joules How much money do you think it might cost?
Calculating Energy Cost If you check your "power" bill you will find that the unit used to measure the amount of electricity used is the kilowatt-hour and not joules. To determine energy cost you must change Joules to Kw-hr 1 Kw-Hr = 3,600,000 Joules
Calculating Energy Cost In our heater example we use 95,040,000 Joules of energy. 95,040,000 ÷ 3,600,000 = 26.4 kw-hr Currently, depending on where you live, a kilowatt-hour costs about $0.09 (9 cents). So our heated used $0.09 x 26.4 = $2.40 Not much… But in a year it adds up.
Measuring Electricity at home All appliances, when new, must have a sticker attached that indicates some of the electrical properties of the unit. Look at the sample appliance sticker below. Circled in red is important electrical information. We can use this information to calculate the energy cost as we did in the last example!
Measuring Power (Part 2) Power is the measurement of how fast work is done. We can also write power as: Power = work divided by time (work in joules, time in seconds, power in watts). P=W ÷ t
Measuring Power (Part 2) Example A crane lifts a 200N crate out of a 6 meter deep hole . If it takes 5 second to complete the task, how powerful is the cranes engine? Given: F=200N d=6m t=5s Solution W=fxd P=W ÷ t W=(200)x(6) = 1200 J P=(1200) ÷ (5) P=240 Watts Worksheet: Power and energy
Energy and Efficiency Systems that use energy to do work are not 100% efficient. Some of the work input is turned into undesired forms of energy such as heat and sound instead of useful work.
Energy and Efficiency Only about 15% of the energy from the fuel you put in your tank gets used to move your car down . The rest of the energy is lost to engine and driveline inefficiencies.
Energy and Efficiency At the power plant, some 60 percent of the energy is lost as waste heat. Another 10 percent is lost in electricity lines and transformers before the electricity even reaches your home.
Energy and Efficiency The efficiency of a system is mathematically determined by the ratio of work output to work input expressed as a percent Efficiency = (work output ÷ work input) × 100%
Energy and Efficiency Example A winch use 120J of work to lift a 10N weight 8m high. How efficient is it? Given: Work (in) = 120 J Work (out) = ? Efficiency=? Solution: Work (out) = Fxd = 10x8 = 80J Efficiency = (work output ÷ work input) × 100% = (120 ÷80) x 100% = 67% The winch is 67% efficient.
Grade 9 Tech. Module Topic 3 Schematics
Schematics A schematic is a diagram that represents parts of a system using, symbols rather than realistic pictures. You should know some of the common Electrical symbols cell battery lamp
Schematics LED resistor (load) switch
Schematics ammeter voltmeter variable resistor
Schematics Can you draw the schematic?
Pictorial Drawings Pictorial drawings are three dimensional drawings that look similar to a picture. There are two basic types. They are: - Oblique - Isometric
Isometric The isometric drawing is most commonly used when constructing a set of drawings. Notice, front and side are at 30 degrees to the vertical.
Isometric The faces of isometric are labeled by their location.
Orthographics Often the faces are drawn separately when developing a drawing… this is called an Orthographic. An Orthographic projection is a series of drawings that show various views of the object.
Activity • Part 1 - Software- Isometric Drawing Tool • http://illuminations.nctm.org/ActivityDetail.aspx?ID=125 • Handout: Illuminations Isometric Views • Part 2 - Building with blocks. • Examine objects. • Sketch the Orthographic for each. • Examine an orthographic • construct the object using the blocks
Production Methods A number of methods are use to produce products. These may include: 1. Separating 2. Combining 3. Forming 4. Conditioning 5. Finishing
Examples 1. Separating • use of a knife, chisel, plane, or saw to cut (separate) materials
2. Combining • use of a nail, screw, staple, or glue to combine materials.
3. Forming • Use of heat and steam to form or shape materials
4. Conditioning • Use of chemicals to condition or protect materials
5. Finishing • Use of sandpaper, buffing compound, or paint to smooth and/or ‘beautify’ a project