Agriculture Technology Paper 1 2015 Questions and Answers Part 2

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Question 3


How can the energy produced from this device be stored efficiently for use during windless days?


Three disadvantages of wind energy that will influence your choice when choosing an alternative energy source:

  • The main disadvantage regarding wind power is down to the wind՚s unreliability factor.
  • In many areas, the winds strength is too low to support a wind turbine or wind farm.
  • Wind turbines generally produce a lot less electricity than the average fossil-fueled power station, requiring multiple wind turbines to be built in order to make an impact.
  • Wind turbine construction can be very expensive and costly to surrounding wildlife during the build process.
  • The noise pollution from commercial wind turbines is sometimes similar to a small jet engine.
  • Protests and/or petitions usually confront any proposed wind farm development.
  • People feel the countryside should be left intact for everyone to enjoy its beauty. (Any 3)

Heat energy that is extracted from the earth՚s inner core:

Geothermal energy

Two important issues that can be raised during the initial survey phase before the exploration of the energy source commence:

  • Is the rock soft enough to drill through?
  • Do the rocks deep down contain sufficient heat?
  • Will this heat be sustainable for a significant amount of time?
  • Is the environment fit for a power plant? (Any 2)

Three advantages of bio-fuel:

  • The main advantage that bio-fuel has over other energy sources is the cost factor.
  • With the ever-increasing prices of crude oil, bio-fuel offers a cheaper solution to our energy needs. One of the main reasons for this low cost is that bio-fuels are made from plant and animal waste.
  • Biodegradable and do not harm the environment when combusted.
  • They are also comparatively lot less polluting. Lesser carbon emissions mean that these fuels are environment friendly, which is the need of the world today.
  • For conventional fuels it takes years to regenerate whereas there is no such problem for bio-fuels.
  • Doesn՚t require any radical changes to switch to the use of bio- fuels, unlike the difficulties in switching to other renewable energy sources such as solar and wind power.
  • Are renewable sources of energy as you can just keep producing more.
  • Ethanol is very inexpensive to produce.
  • Can help prevent engine knocking. (Any 3)

Two common alternative fuels that are obtained from plant origin:



Explain the process that takes place in solar panels to transform sun energy into electricity:

  • When photons, contained within the sun՚s rays, hit the solar cells, the electrons absorb this solar energy.
  • The electrons are transformed into conduction electrons.
  • When the energy of these photons is great enough, the electrons can become free.
  • The electrons now carry an electric charge through a circuit to the destination.

Four disadvantages of solar energy:

  • Some areas of the world are not able to benefit from photovoltaic energy.
  • Due to the climate, weather patterns, or high levels of pollution.
  • Sun energy is not available during the nighttime.
  • A cloudy day makes this energy source ineffective.
  • Produce low amounts of energy at low voltage and amperage. (Any 4)

Question 4

Skills and Construction Processes

Two reasons for this problem:

  • The torch is too close to the metal.
  • The welding pool is too hot.
  • Welding current is too low. (Any 2)

TWO methods of solving this problem:

  • Use pliers to remove the blob.
  • If the tip is totally blocked, unscrew, and replace.

Two reasons for the occurrence of welding spatter when using the MIG-welding machine:

  • Inadequate induction.
  • Voltage is too low.
  • Gas supplies not enough.
  • Metal is dirty or wet.

Two measures that can be applied to solve the problem of welding spatter:

  • Increase the gas supply to the required reading.
  • Increase the current.
  • Increase the voltage.
  • Clean the surface with an angle grinder.

‘Welding galvanized steel is very dangerous.’ Give Two reasons:

  • Galvanized steel contains a zinc coating that produces poisonous carcinogenic gas when it is burnt.
  • Exposure to this substance results in heavy metal poisoning. (Poisonous gasses are given off)

Correct process of overhead arc-welding:

  • 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)

Three hazards to take into consideration when working with the plasma cutter:

  • Fire hazard.
  • Vision hazard.
  • Breathing hazard.
  • Electrical hazard.

Freehand top-view sketch of your design to protect the ball valve mechanism:

Marks will be allocated for the following:

  • Functionality of the drawing.
  • Indicate the position of the 2 types of metal profiles that is going to be used in the manufacturing process of the grid.
  • 500 mm and 600 mm (any applicable length)
  • Butt and T- joints
Functionality of the Drawing

Cutting list:

  • 2 lengths angle iron of mm.
  • 2 lengths angle iron of mm.
  • 5 lengths flat bar of mm (correlate with sketch) .

Method that can be used to prevent the metal grid from rusting:

Painting with a rust resistant paint.

Two types of metals that can be cut by using an oxyacetylene cutting torch:

  • Mild steel
  • Cast iron
  • Stainless steel

Explain the oxyacetylene cutting process from the moment the flame has been lit up to the moment that the cut is finished.

  • Heat the material until it is red hot.
  • The steel turns into a liquid.
  • Oxygen is then fed with the lever on the cutting attachment.
  • The liquid iron is cleared from the cut by pressure from the oxygen stream.
  • The steel ignites giving off more heat to keep the process going.