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Work and conversion of energy

Module by: Siyavula Uploaders. E-mail the author

NATURAL SCIENCES

Grade 9

ENERGY: FORCES AND MACHINES

Module 21

WORK AND CONVERSION OF ENERGY

Activity 1:

Describing the relationship between effort and energy with reference to a turbine

[LO 1.2, 2.1, 3.2]

Energy is necessary for any performance of work. This energy must be obtained from FUELS or from CONVERTED forms.

CONSTRUCTING A SIMPLE TURBINE

  • Use a tin lid, cut it into segments to form it into a fan and make a hole in the centre.
  • Nail the fan to a piece of wood.
  • Boil water in a kettle, until there is a strong draught of steam.
  • Hold the fan in position so that the jet of steam will be directed towards its centre.

Figure 1
Figure 1 (Picture 1.png)
  • QUESTIONS

1. What happened?

2. What kind of energy conversion occurred?

3. Describe the form of energy conversion that occurs with wind towers such as those that have recently been erected along the West Coast in the vicinity of Malmesbury.

Figure 2
Figure 2 (graphics1.png)

4. What advantages do wind towers like these have for the environment?

  • Write a paragraph (60 words) about the value that the principle of the turbine has for people.

  • WORK is also measured in (give the name of the unit) .…………....................................

Activity 2

Discussing other machines that operate by means of conversion of energy

THE MICROSCOPE

  • As long ago as the early 17th century, Robert Hook assumed that light rays have energy and that a wound-up spring has potential energy. He also constructed the first microscope and was the first person to use the universal lever, which is used in a wide range of instruments and cars.

SATELLITES

  • Satellites depend on solar panels to absorb light energy from the sun and supply electricity for all other electronic functions and for cameras and radio equipment. Energy is also stored in chemical form in rechargeable batteries.

WIND PUMPS

  • The blades of the rotary disk are turned by the wind to drive a pump that pumps underground water to a storage dam.

Assignment 3: GROUP DISCUSSION

  • Name at least three other machines that operate by means of energy conversion and explain the workings of each one.

WHEN IS A MACHINE MECHANICALLY INEFFECTIVE?

  • When a machine or appliance fails to provide an adequate quantity of the energy that it has been designed to provide we say that it is in affective.
  • The light bulb, for instance, releases (unwanted) heat, but was actually designed to provide light!
  • In this instance, fluorescent lighting is more effective and economical.
  • Are you able to list further examples?

Assessment

Table 1
LO 2
Scientific KnowledgeThe learner will know and be able to interpret and apply scientific, technological and environmental knowledge.
This is displayed when the learner:
2.1 is able to recall meaningful information;
2.2 is able to arrange information according to categories;
2.3 is able to interpret information;
2.4 is able to apply knowledge.
LO 3
Science, Environment and the CommunityThe learner will be able to demonstrate an understanding of the interrelationships between science and technology, society and the environment.
This is displayed when the learner:
3.1 is able to show appreciation of science as a human endeavour;
3.2 is able to recognise the value of sustainable utilisation of resources.

Memorandum

Activity 1

Questions:

1. The fan (‘turbine’) rotates

2. Chemical to steam to kinetic / mechanical

3. Kinetic to electrical to chemical

4. Natural resources (e.g. coal) are not used and pollution is avoided

Paragraph:

  • E.g. natural energy is converted to usable energy
  • Without consumption of resources
  • Without pollution
  • There are no waste products to be got rid of
  • Examples of utilising turbines: generation of electricity, previously also for driving mills

Effort is measured in Joule

Activity 2

  • Any power generator
  • Compressor
  • Vehicle engine
  • Sewing machine
  • Kitchen appliances
  • Etc.
  • Ineffective machines: any machine or system that releases energy in a non-usable form, e.g. a car that is driven with the hand break on (much energy is wasted in the attempt to overcome the force of friction – energy in the form of heat goes to waste).

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