Introduction
This section of the syllabus deals with the use and transformation of energy to achieve solutions to practical problems. This section should not be treated to the same depth as in a science lesson. It is important that students be able to understand the principles and use of various machines and components so as to be able to include them in the design of solutions to tasks. Care should be taken however to use the proper units and symbols associated with this section. Students should be able to identify the use of mechanisms in everyday situations and recognise and describe the types of motion and motion change involved. As an example of the possible integration of Structures, Mechanisms and Technology & Society, the bicycle could form the basis of an assignment.
Syllabus ExpansionNotes and Comments
Energy Recognition of the following forms of energy: mechanical, chemical, electrical, heat, light and sound. Energy as the ability to do work i.e. cause movement Devices that convert energy from one form to another, described as simple input-output systems using block diagrams. Energy cannot be created or destroyed, it can only be changed from one form to another.
The electric motor, loudspeaker, light bulb, dynamo, turbine, pump, windmill etc. can be used as the basis of study of energy conversions.
Electrical energy is sold by the E.S.B. in units of kilowatt-hour (kWhr)
Students should know that, while energy itself is conserved, the sources of energy in its different forms do not remain constant. This is a useful opportunity to deal with such aspects of Technology & Society as energy sources, the environment, conservation, pollution, safety & health.
Students should be able to identify renewable and non- renewable sources of energy.
Syllabus Structures
Expansion
A structure is an assembly or arrangement of members of selected materials, arranged in a manner that maintains its general shape under load. Unit of force - the newton(N). Identification of the various types of forces acting on a structure. Types such as tension, compression, bending, shear, torsion etc., with examples that clearly illustrate their differences as used in span, strut, tie. Role of triangulation.
Notes and Comments
Students should be able to recognise common structures in everyday use and identify the force(s) present. Student will need to consider the nature and properties of the material being used in a structure, and such aspects as safety, function, aesthetics, etc.
The student will need to appreciate the need for stability, rigidity and equilibrium. Suggested task: Construct a structure to span a gap of 2 m and hoM upa load of 2 N. The materials to be used could also be specified so as to close the task.
Syllabus Mechanisms
Types of motion and motion change
Expansion
A mechanical device is made up of one or more mechanisms which shape and transform motion and force. Different types of motion: linear, rotary, oscillatory, reciprocating. Transmission of motion
- linear to rotary and vice versa
- rotary to rotary;
- rotary to reciprocating and vice versa;
- oscillatory to rotary and vice versa.
Notes and Comments
Investigation, classifying and describing different types of motion as evidence by trolley, gears, shafts etc. Students should be able to recognise the common mechanisms in everyday use (bicycle, blender, washing machine etc.) and recognise the types of motion involved.
Expansion
Application of Mechanisms Lever levers as linkages Screw Screw ( also nut & bolt ) as a means of rotary to linear conversion and vice versa. Pulley Fixed pulley to change direction of motion; simple applications Others Belts and chains, gears used in the transmission and transformation of energy and motion; Clutch used to facilitate the safe meshing/unmeshing of gears in transmission of power. Effects of friction and need for lubrication.
Notes and Comments
Mechanical advantage in different types of levers (calculations not required).
Not all mechanisms need be studied. Suggested task: Construct a mechanism to lift a load o f l O N througha height of 2 m
Syllabus Electric Circuits
Expansion
Flow of charge from one point to another in a circuit.
Direct Current Electric Current (/) Unit of current, ampere [A]. Measurement; use of ammeter.
Voltage (Potential Difference) (V) The 'driving' force that causes charge to flow. Unit of voltage, volt [V]; measurement of voltage; voltmeter.
Resistance (R) Unit of resistance ohm [~2] Colour coding of resistors. Measurement of resistance. Ohm's Law V = I x R Circuits
Notes and Comments
Only conventional current need be considered Students should note that polarity is important for some circuit components Charge flows in one direction only when a DC power source is used.
Use of an electric current to include heating, lighting, sound (as in speaker, buzzer), magnetic (as in relay coil) and movement (motor).
Resistors; fixed, variable, light dependent resistor, thermistor.
Simple examples of applications of series and parallel circuits. Potential divider in this context for fixed and variable resistances. Parallel circuits.
Expansion
Fault finding by simple test for continuity and measurement of voltage. Circuit Components Switches Use of switches(simple on/off, pressure, reed, single and double pole, single and double throw, relay). Other Devices Bulbs, buzzers, relays, LDR, thermistor, resistors (including potentiometer as variable resistance) Diode, LED, capacitor, transistor.
Notes and Comments
The multimeter can be very useful for this activity.
Automatic switching circuits as appropriate.
Suggested task: Construct a toy for a small child that lights up andmakes a noise.
Syllabus Electronic Systems
System Input
System Process Decision circuits
Notes and Comments
The systems approach to electronics is recommended here. The understanding of the exact working of each component is not required. Students should have a knowledge of discrete components from their work in assembling circuits. Input sensors to include switch; light (light dependant resistor, LDR), heat (thermistor), potential divider, etc.
(Teachers mafl find it more convenient to useintegrated circuits (IC) when using these circuits.)
! SAFETY
Expansion
Amplification, switching and time delay circuits System Output
Assembly & use of systems
Notes and Comments
Transistor as switch, amplifier; Capacitor as a time delay device in circuits. Buzzer, lamp, relay, motor o r any electrical device which can give a sensory output in the form of light, sound heat or motion.
Assembly of circuits using 'breadboards', commercial prototyping boards or even wooden blocks should be undertaken by the students. A variety o f ways of assembling permanent circuits including insertion into prepared boards, soldering onto track boards or soldering onto prepared printed circuit boards. (It is not intended that students should be required to make the printed circuit beards). Many of the tasks already listed allow electronic solutions.
Syllabus Pneumatics (These topics may beused by students inarriving at thesolution o f tasks, butwill not form thebasis o f questions onexaminationpapers.)! SAFETY
Expansion
Pneumatics seen as a simple system: compressor, valve, cylinder. Use of compressed air as a source of energy. Units of pressure: pascal [Pa] or BAR Use of three port (3PV) and five port (SPV) valves to control single and double acting cylinders, providing linear motion. Use of restrictor to achieve time delay.
Notes and Comments
Commercial pneumatic units for use in school are the most suitable Great care must be taken with any source of compressed air. Reference should be made to the use of pneumatics in industry.
Syllabus
Robotics (These topics may beused by students inarriving at thesolution o f tasks, butwill not form thebasis o f questions onexaminationpapers.)
Expansion
Simple robotic control
Computer Control
Notes and Comments
Use of simple linkages and motors to achieve limited automation as in door openers etc. Use of time clocks or other controlled switching to achieve more complex control involving a number of stages or devices. Use of output port of computer for control of electrically operated devices. Various commercial units are available that allow simple instructions to be entered The computer as the 'process' stage in a system. Computer input by means of programming or by use of supplied software. System output in the form of light, sound, movement, switching, etc.