AGRICULTURAL TECHNOLOGY
GRADE 12
NSC PAST PAPERS AND MEMOS
FEBRUARY/MARCH 2018

MEMORANDUM 

SECTION A 
QUESTION 1 
1.1
1.1.1 C✔✔ (2)
1.1.2 A✔✔ (2)
1.1.3 C✔✔ (2)
1.1.4 C✔✔ (2)
1.1.5 B✔✔ (2)
1.1.6 C✔✔ (2)
1.1.7 B✔✔ (2)
1.1.8 A✔✔ (2)
1.1.9 C✔✔ (2)
1.1.10 A✔✔ (2)  (10 x 2) (20) 

1.2
1.2.1 cell phones✔✔ (2)
1.2.2 flat belt✔✔ (2)
1.2.3 methanol✔✔ (2)
1.2.4 weaker✔✔ (2)
1.2.5 Carbon-dioxide (CO₂ )/dry powder✔✔ (2)  (5 x 2) (10) 

1.3
1.3.1 B✔✔ (2)
1.3.2 E✔✔ (2)
1.3.3 A✔✔ (2)
1.3.4 D✔✔ (2)
1.3.5 C✔✔ (2)  (5 x 2) (10)

TOTAL SECTION A: 40

SECTION B 
QUESTION 2: MATERIALS AND STRUCTURES 
2.1 FOUR safety properties of insulation material 

• Must not be harmful or dangerous to people when inhaled or  touched.✔ 
• Should not burn easily.✔ 
• Rodents and insects must not be able to eat it or build their nests in  it (treated with an anti pest agent).✔ 
• Should be light.✔ (4)   

2.2 2.2.1 TWO measures of ensuring that humans do not  accidently come into contact with an electric fence. 

• Place safety signs on the fence and gates.✔ 
• Don’t erect near or across pathways.✔ (2) 

2.2.2 Reasons for using ceramic insulators between the wire  and the post of an electric fence. 

• It is not a conductor of electricity.✔ 
• Weather resistance/Strong/Durable.✔ (2)
• 2.2.3 Function of the appliances shown in the picture. 
• It applies tension on the wire of an electric fence.✔ 
• When the fence wire loses its tension it is not necessary  to loosen the wire, it can be wind up with this appliance.✔ (2) 

2.2.4 Description of what will happen to a person when he/she  touches an electric fence if the amperage is too high. 

• The result of too high amperage will be that a person will  sustain a lethal shock that can cause tissue damage✔ or  heart failure.✔ (2) 

2.2.5 TWO types of batteries that can be used as a power  source for an electric fence energizer. 

• 12v dry disposable battery✔ 
• 12v wet rechargeable battery✔ (2)

2.2.6 Factors that have an influence on the earth return cycle  of an electric fence. 

• There must be a return path through the ground and an  earth spike back to the energizer in order to complete the  loop.✔ 
• The animal is the missing link that completes the loop.✔ 
• Vegetation will also complete the loop causing the output  voltage of the energizer to drop.✔ 
• Therefore it is very important to keep any growth on the  line to a minimum to ensure the animal receives the  maximum shock from the energizer.✔ (4) 

2.2.7 THREE ways of increasing the earth efficiency for  particularly poor earth conditions like very dry soil.   

• Increasing the number of earth spikes.✔ 
• Run an earth return wire in parallel to the fence line and  connecting it to earth spikes at regular intervals.✔ 
• Using copper plates in the ground.✔ (3)

2.3 FOUR uses of Teflon on a farm. 

• Automobile wiper blades✔
• Carpet or fabric protector✔
• All-weather clothing✔
• Coating for eyeglass lenses✔
• Magazines for guns✔
• Teflon coated cooking pans✔
• Teflon tape for sealing  fittings✔ 
• Car wash products✔
• O-Rings✔ 
• Oil and water seals✔
• Teflon Taps and fitting✔
• Non-return valves✔
• Flanges✔ 
• Pipe saddles✔ (Any 4) (4)

2.4 THREE different applications of Vesconite on farm implements. 

• Bushes✔ 
• Solid rods✔ 
• Wear plates✔ (3)

2.5 Bronze used to manufacture propellers of huge ships. 

• Ships spend all their life in seawater that is highly corrodible.✔ 
• Bronze is the most cost effective metal because of its resistance  against corrosion by seawater.✔ (2)

2.6 FIVE influences that manganese have on stainless steel.  

• It combats corrosion.✔ 
• Gives steel a coarser structure.✔ 
• Changes the band structure, at the same time causing a reduction  in striking strength.✔ 
• Increases tensile strength.✔ 
• Reduces the critical cooling tempo and by doing so improves  hardening.✔ 
• Increases resistance against wear.✔ 
• Reduces magnetism.✔ (Any 5) (5) [35]

QUESTION 3: ENERGY 
3.1
3.1.1 FIVE different types of renewable energy sources used by  modern society. 

• Solar energy✔ 
• Wind energy✔ 
• Hydro energy✔ 
• Geothermal energy✔ 
• Bio energy✔ 
• Tidal energy✔ (Any 5) (5) 

3.1.2 The geothermal source protection from cooling down too  much. 

• Do not pump too much cold water into the hole✔ (1) 

3.2
3.2.1 Factors that have a negative influence on the effectiveness  of a solar energy cell.  

• Climate, weather patterns✔ 
• High levels of pollution✔ 
• Sun energy is not available during the night time✔ 
• A cloudy day makes this energy source ineffective✔ (4) 

3.2.2 TWO types of energy that are directly generated from solar  energy. 

• Heat✔ 
• Electricity✔ (2) 

3.2.3 A device used with solar panels that change direct current  to alternating current. 

• Inverter✔/transformer✔ (1) (Any 1) 

3.3
3.3.1 TWO actions to prevent the blades from being damaged when they turns too fast during a strong wind storm. 

• Change the pitch of the blades✔ 
• Apply the brakes✔ (2)

3.3.2 FIVE advantages of a small wind energy system to the  farmer. 

• Decades of free electricity after initial-cost recovery.✔ 
• Increased property values.✔ 
• Reliable electricity.✔ 
• Relief from high and volatile prices of other forms of  electricity.✔ 
• Personal energy independence.✔ 
• Ability to support clean energy and reduce global warming.✔ (Any 5) (5) [20]

QUESTION 4: SKILLS AND CONSTRUCTION PROCESSES 
4.1
4.1.1 THREE of the most possible causes of poor penetration during MIG  welding. 

• Current too low✔ 
• Preparation too narrow✔ 
• Root face too large✔ 
• Root gap too small✔ 
• Worn contact tip causing irregular arc✔ 
• Incorrect alignment of plates✔ (Any 3) (3) 

4.1.2 Reason why it is not necessary to use additional flux when MIG  welding. 

• The shielding gas (CO2) replaces the flux✔ (1) 

4.1.3 TWO reasons why MIG welding is quicker than conventional arc  welding. 

• Rod is not changed regularly✔ 
• Flux does not have to be removed✔ (2) 

4.1.4 Type of material used for manufacturing suitable protective clothing  for welding.  

• Cotton✔ (1)

4.1.5 A reason for your answer in QUESTION 4.1.4 

• Other synthetic materials melt when exposed to heat/cotton does not melt  when exposed to heat✔ (1) 

4.1.6 Explanation of why a little metal ball occurs on the tip of your MIG  welding torch. 

• The gap between the welding tip and the work piece is too small.✔ 
• You are building up too much heat because the current setting is too  high.✔ (2) 

4.1.7 TWO ways of clearing the metal ball from the tip of the MIG welding  torch. 

• Use pliers to remove the blob of welding from the nozzle.✔ 
• Use a file or small grinder to remove the blob.✔ 
• In severe cases, replace the nozzle.✔ (Any 2) (2)

4.1.8 TWO different metals that can successfully be welded with a MIG  welding machine.  

• High alloy steel (stainless alloys)✔ 
• Aluminium✔ 
• Mild steel✔ (Any 2)  (2) 

Related Items

4.2 Explanation on how you will achieve a neat final welded joint with the angle  grinder. 

• Use a grinding wheel on the angle grinder.✔ 
• Be careful as you approach the surface of the original stock. You don't want to grind through your nice new weld.✔ 
• Move the angle grinder around like you would a sander so as not to heat up, or  grind away any one spot of the metal too much.✔ 
• If you see the metal get a blue colour to it you are either pushing too hard with  the grinder or not moving the grinding wheel around enough.✔ 
• Wear a full face mask when grinding, a mask or respirator, and ear  protection.✔ (5)

4.3 The overhead arc welding procedure. 

• Use an arc as short as possible.✔ 
• Weld a number of runs without any lateral movement.✔ 
• When molten metal starts dripping, the amperage should be reduced slightly.✔
• Move electrode slightly faster.✔ 
• Hold electrode in same position as in relation to base metal.✔ (Any 4) (4)

4.4
4.4.1 A device that can be used to light the flame of an oxy-acetylene torch.

• Always light the oxyacetylene torch with the striker.✔ (1) 

4.4.2 Explanation of why it is NOT advisable to use a cigarette lighter or  matches when igniting the oxyacetylene torch. 

• A cigarette lighter or match would put your hand too close to the ignition  tip.✔ (1)

4.4.3 The procedure that must be followed to shut down the oxy-acetylene  equipment after welding is finished. 

• Turn off the acetylene valve on the torch handle.✔ 
• Turn off the oxygen valve on the torch handle.✔ 
• Turn the main cylinder valve clockwise on the top of both gas  cylinders.✔ 
• Now open the two valves on the torch handle to 'bleed' the system.✔ 
• Turn both the oxygen and acetylene regulator handles counter clockwise until they are loose.✔ 
• Close both valves on the torch handle. (Any 5) (5) 

4.5 Explanation of how to deal with hazardous gasses when using a plasma  cutting torch. 

• Under no circumstances inhale these gases.✔
• If you must inspect a piece as you cut it, view the piece from the side, not from above. This will minimize your exposure to hazardous gas.✔
• Make sure the work area is well-ventilated as well.✔
• An exhaust hood or a space open to the outside is recommended when using a plasma torch.✔
• Respirators or other breathing apparatus may be required.✔(5) [35]

QUESTION 5: TOOLS, IMPLEMENTS AND EQUIPMENT 
5.1 5.1.1 Identify component A. 

• Auger✔ (1)

5.1.2 The function of the ram. 

• The hay is compressed in the baling chamber by the ram✔ with a  forward backward movement.✔ (2) 

5.1.3 TWO functions of the slip clutch found in the drive mechanism of  a baling machine. 

• To prevent heavy objects from being taken into the baler.✔ 
• To protect the pick-up if it is impeded by anything.✔ 
• To protect the auger if it becomes overloaded.✔  (Any 2) (2) 

5.1.4 FIVE procedures that must be followed before the baler is  stored for a long period. 

• Remove all bales from baling chamber.✔ 
• Clean the baler properly.✔ 
• Drain and replace all oil.✔ 
• Releases the tension on all drive belts.✔ 
• Remove all chains, clean and oil them, and replace them.✔ 
• Dismantle all slip clutches, clean them and reassemble them but  do not put the springs under tension.✔ 
• Totally reduce bale chamber tension.✔ 
• Cover all unpainted areas with a thin layer of grease.✔ 
• Grease all grease nipples.✔ 
• Store baler in a dry place under cover.✔ (Any 5) (5) 

5.2 Reason why it is necessary to make use of a four-wheel drive tractor  with a front-end loader mechanism, to move large round bales. 

• The front suspension and wheels are stronger to carry the weight of the  bales.✔ (1) 

5.3
5.3.1 Calculation of the diameter of pulley A on the pump.

• Na x Da = Ng x Dg
  Diameter of Driven pulley Dg = 3 750 x 200✔ 
                                                       2 000✔ 
  Dg = 375✔ mm✔ (4)

5.3.2 FOUR advantages of V-belts. 

• V-belts do not easily slip off pulleys.✔ 
• V-belts draw tighter round pulleys when tension increases.✔ 
• Lubrication is never necessary.✔ 
• V-belts are relatively strong, and under normal circumstances do  not easily break.✔ 
• Cold, moist conditions, age or use do not cause V-belts to stretch  or shrink.✔ 
• V-belts last longer than flat belts.✔  (Any 4) (4)

5.4
5.4.1 Meaning of illustration of arrow A. 

• The illustration shows how the plough✔tends to push down the front  wheels✔when a top link✔ is fitted between the plough and tractor. (3) 

5.4.2 THREE ways a farmer could make use of to change a tractor`s  mass displacement positively. 

• Decrease the tow bar pulling force✔ 
• Lower the tow bar✔ 
• Increase the wheelbase✔ (3) 

5.4.3 THREE factors that have an influence on the forward movement  of the tractor when ploughing. 

• Ploughing depth✔ 
• Soil resistance✔ 
• Forward speed of the tractor✔ (3)

5.5 The reason why a differential is installed in the rear axle of a tractor.  

• Changing direction of rotation✔ 
• Speed reduction✔ 
• Dividing rotation equal between the rear wheels✔ 
• Increase torque✔  (Any 3) (3)

5.6 FOUR causes of tractor that overturns. 

• Cornering at high speed.✔ 
• Driving off the shoulder of roads.✔ 
• Working on a steep ditch, hill or washout.✔ 
• Carrying loads too high in the front-end loader.✔ 
• Hitching too high when pulling heavy loads.✔ 
• Towing loads downhill too fast and/or without sufficient brakes.✔ 
• Sliding off loading ramps.✔ 
• The load on the trailer more than 75% of the tractors weight.✔  (Any 4) (4)

5.7 TWO places where the sensitivity element can be installed on a tractor. 

• Where the top link is fitted✔  
• In the differential housing✔ 
• At the base of the lifting arms✔  (Any 2) (2)

5.8 The medium that is used to drive each tool. 

1. Air ✔
2. Oil✔
3. Electricity✔ (3) [40]

QUESTION 6: WATER MANAGEMENT 

6.1 FOUR types of filtering systems used to purify water for human  consumption and describe the working of each. 

• Distillers’ purification system✔
  • They work with a boiling water/evaporation system.✔
• Reverse Osmoses purification system✔ 
  • It works through a liquid system and through a membrane very  slowly in molecule level.✔
• Whole house purification system✔
  • Use cartridges to filter water.✔
• Faucet water filters✔ 
  • Installed in the kitchen and cleaned water as needed.✔
• Jug /Pitcher filters 
  • The water will go in at the top and slowly filter down and finally  captured at the bottom in a reservoir. (Any 4 x 2) (8) 

6.2 Meaning of abbreviation 'GIS' and the use of it in a modern farming  enterprise. 

• GIS : Geographical Information System✔ 
  • Remote sensing image data from the soil and crops is processed and  then added to the GIS database.✔ 
  • This data is analysed and interpreted.✔ 
  • Problem areas or areas of under production in fields are identified.✔
  • The problem areas can then be rectified by adding extra water or  fertilizers.✔ (5) 

6.3 Reasons for determining the flow rate of water in an irrigation  system. 

• To ensure the correct calibration of the sprayers.✔ 
• Effective scheduling of irrigation.✔ 
• To prevent the over utilization of the water source.✔ 
• To use water economically.✔ (2) (Any 2)   

6.4
6.4.1 The most important substance that is found in any septic  drain that ensures that it will function properly. 

• Bacteria✔ (1)

6.4.2 The function of the distribution box of a septic drain. 

• Serves to distribute the flow from the septic tank overflow  evenly to the absorption field or seepage pits.✔ 
• It is important that each trench or pit receive an equal amount  of flow.✔ 
• This prevents overloading of one part of the system.✔(3)

6.4.3 THREE places where a septic drain should not be build. 

• Near boreholes or drinking water installations.✔ 
• Near the farmhouse.✔ 
• Near traffic.✔ 
• Where people usually eat, wash or work regularly.✔ (Any 3) (3)

6.5
6.5.1 The use of the irrigation timer. 

• This device controls the watering through different irrigation  lines.✔ 
• This device can start and stop the irrigation system.✔ (2) 

6.5.2 TWO basic types of irrigation timers that can be used on a  farm. 

• Mechanical timers✔ 
• Electronic timers✔ (2)

6.5.3 FOUR different types of irrigation systems. 

• Overhead irrigation systems✔ 
• Centre pivot irrigation systems✔ 
• Sprinkler irrigation✔ 
• Travel irrigation system✔ 
• Wheel line irrigation system✔  (Any 4) (4)

[30] 
TOTAL SECTION B: 160
GRAND TOTAL:   200