Basic Technology JS1

JS1 Note on Basic Tech.

                                      TECHNOLOGY

Definition:

Technology can be defined as the scientific knowledge used in practical ways to meet and satisfy human needs and comforts.

We can also say Technology is the method or processes by which people produce or process what they eat, drink, wear and use.

Meaning of Technology:

A very long time ago, man carried out all his activities manually. For instance, transportation was mainly on foot. All food processing were done manually and laboriously. Later, man used beasts of burden like camels, horses, and donkeys as means of transportation. 

Technology is needed by man to meet and satisfy his needs with maximum comforts.

Types of Technology:

(i)               Highly Developed Technology involves the methods of carrying out any work through the use of machines e.g. Tractors, combine harvesters, refrigerators, micro-waves.

(ii)             Under Developed Technology involves the use of manual processes e.g. use of cutlass for weeding, the use of hook and net for fishing, trekking, using grinding stone to grind food ingredients etc.

Arms/Segments of Basic Technology:

Basic Technology as a subject deals with the following aspects:

(i)          Technical Drawing

(ii)        Ceramics

(iii)       Electricity

(iv)      Building construction

(v)        Metal works

(vi)      Electronics

(vii)     Woodwork

(viii)   Plastics

Products of Technology:

Some products of technology are:

(i)               Calculator

(ii)             Ceiling fan

(iii)           Computer

(iv)          Motor vehicles

(v)            CD/DVD players

(vi)          Drum set

(vii)        Photocopy  machine

(viii)      Oven

Exercise for week1  Basic Technology (JS1)

Instruction: Outline differences between under-developed and highly developed technology

Economic Activity	Under-Development Technology	Highly-Developed Technology
FARMING
COMMUNICATION
LIGHTING
FISHING
TRANSPORTATION
FOOD
HUNTING

TECHNOLOGY AND SOCIETY

Technology is not necessarily ‘transferred’, it is developed. People develop technology when they improve their knowledge, skills and procedures for making, using and doing things.

Technology leads to economic development of the community where it is used. Technology can be applied to all aspects of human endeavours, be it religion, politics, banking, social, business, academics and sports.

All the countries in the world have been blessed by nature.  Abundant natural resources at their disposal, but only countries with a well-developed technology makes maximum use of her gifts for the benefit of her people.  Countries with under-developed technology cannot make adequate use of their natural resources. Such countries will sell her raw materials at low prices to developed countries. For instance, Nigeria exports her crude oil to USA ‘cheaply’ rather than refine the raw material here then export finished products to countries so as to make more income. Such situation is akin to a farmer who has a large piece of land for farming but still beg people to give him food to eat.

Poor or under-developed technology can lead to shortage of food and clothing, poor shelter, poor health, inefficient means of transportation and communication and ineffective internal and external security.

A good educational system is the bedrock of developed technology. It encourages people to make use of both their brains and hands to acquire suitable knowledge and skills to design and produce methods and processes that will enable them to make maximum use of their resources for the benefit of the society.

Exercises:

1.      What are five ways in which technology has improved standards of living?

2.      Why do we need technology literacy?

3.      How can you briefly describe each of the stages in technology?      

Research:

1.      What are workshop tools?

2.      What is a workshop?

                                     

WORKSHOP SAFETY: DEFINITION, SAFETY RULES, SAFETY DEVICES

What’s a workshop?

A workshop is a place where engineering works are being carried out by the professionals or experts.

Examples of workshops are:

1.      Carpentry workshop

2.      Welding workshop

3.      Auto mechanic workshop

4.      Electrical workshop

5.      Sculpting workshop

Accidents

An accident is an unexpected negative event or experience that happens to somebody. Accidents can occur in the workshop.

A Workshop Accident is a harm or injury that is done to someone in a workshop. Accidents are caused by people and equipment used in the workshop.

Some causes of workshop accidents:

1.      Lack of provision of safety devices

2.      Failure to follow laid-down methods for handling facilities and devices

3.      Failure to use safety devices provided

Safety Rules   are instructions that professionals and workshop users obey before an activity to prevent danger or risk during the activity.

Some safety rules are:

1.      Do not operate any machine or use any tool without a prior knowledge or having being instructed on how it should be used.

2.      Always wear an overall while in the workshop.

3.      Always wear hard covered shoes with hard soles.

4.      When in doubt, always ask.

Safety devices

Safety devices are those devices that are designed or made to prevent injury or accidents. Some safety devices reduce the extent of injury to humans and damages to equipment.

We can also define Safety Devices as devices that work to help secure the safety of anyone who is using them.

Some safety devices are:

1.      Fire fighting equipment:

                                     i.            Bucket of sand

                                   ii.            Bucket of water

                                  iii.            Fire extinguisher

2.      Safety glasses and goggles

3.      Gloves

4.      First-aid kit

5.      A phone (to dial emergency numbers in case of extreme accidents)

Exercises:

1.       What is a workshop?

2.       What is an accident?

3.       What is a workshop accident?

4.       What are safety rules/precautions?

5.       What are safety devices? Mention four safety devices?

Research:

1.       What is an accident?

2.       Describe workshop accidents.

3.       Mention three safety devices.

4.       Mention four types of wood.

5.       Mention three uses of wood.

IDENTIFICATION OF WOOD

We get wood from trees. Tress can be found in the forest, farms, gardens, and along the streets. The longer trees are left the bigger and taller they grow. When there are well grown, they are ‘fell’ and taken to the Saw-Mill where they are cut into marketable sizes.

Wood is one of the commonest used materials because it is light, strong and be worked upon easily. Wood is used in making furniture and cabinets.  Wood is used in building construction too.

The major parts of a tree

1.      Root: this holds the tree firmly to the ground. The roots search for various mineral salts in the moist ground. From the roots, water and mineral salts are carried upward to the leaves.

2.      Trunk or stem: this part acts as a support for the branches, which it raises as high as possible towards the light. It is from the stem or trunk that we get our timber.

CLASS ACTIVITY: describe the following parts of a tree:

1.      Branches:____________________________________________________________________________________________

2.      Leaves:_______________________________________________________________________________________________

3.      Bark:_________________________________________________________________________________________________

The Structure of Wood

Wood is made up of a number of tiny-like units called cells. These cells are called Fibres or Tracheid. They vary in length, but the strength of the wood primarily depends on the thickness of the cell walls.

Features of wood

As shown in the diagram above, when a tree is felled the cross-section will show the Pith, the Back or Curtex, the Sapwood, the heartwood, the annual rings,  the cambium Layer, and the Medullary Rays

Class Activity: Describe the following parts of the cross section of a tree:

1.      The cambium layer:

2.      Sapwood:

3.      Heart wood:

4.      Medullary Rays:

5.      The Annual Growth Ring:

6.      The  Pith:

7.      The Back or Curtex:

Wood Processing:-  Wood can be fell from two different areas, which are the free area and the forest reserved area. The wood can be transported to the  sawmill through Lorries, river or rail.

Wood Conversion is the cutting of splitting of wood into marketable sizes.

WOOD SEASONING:

Wood Seasoning is the removal of water or moisture content in wood.

Method of wood seasoning:

1.      Artificial Seasoning: through the use of ‘kiln’

2.      Natural seasoning: through air drying.

Reasons for seasoning wood:

1.      It makes the wood more durable

2.      It makes the wood lighter in weight

3.      It reduces the moisture content

4.      It makes the wood more stable

5.      It minimizes or prevents attacks from water, bacteria and fungi.

 

Calculation of the Moisture Content of wood

The moisture content of the timber can be calculated using the formular:

Moisture Content (M.C) = (weight of wet wood – weight of dry wood)   x  100

                                                         Weight of dry wood

Example: A piece of timber weighed 120kg before drying and 100kg after drying. Find the moisture content of the timber.

Solution:

Wet Wood = 120kg

Dry Wood  =  100kg

M.C. =(weight of wet wood – weight of dry wood)   x  100

                          Weight of dry wood

M.C.= (120 – 100)    x   100

                 100                1

M.C. = 20%

Class Exercise:

1.      A piece of timber weighed 88kg before drying and 70kg after drying. Find the moisture content of the timber.

2.      Mention 10 uses of wood.

Wood Preservative

This is a process of treating wood with chemicals called preservatives to prevent insects’ attack and therefore prolong the service life of the wood.

Methods off Applying Preservatives;

1.      By using brush

2.      By using pressure treatment

3.      By spraying

4.      By dipping

Types of preservatives:

1.      Tar oils

2.      Water borne

3.      Solvent type

Exercise:

1.      What is wood?

2.      What is the main source of wood?

3.      What are the major parts of a tree?

4.      How can the cross section of a tree be drawn and label it correctly?

5.      What are the parts of the cross section of a tree?

6.      What is wood processing?

7.      What is wood conversion?

8.      What is wood seasoning?

9.      What are the two major types of seasoning?

10.  Why is wood seasoning recommendable?

11.  How can you calculate the Moisture Content of a piece of timber that weighed 120kg before drying and 100kg after drying?

Research:

1.      What is metal?

2.      What are the three main types of metal?

3.      What is Metal Processing?

4.      What is a furnace?

5.      How can a furnace be described?

IDENTIFICATION OF METAL

A metal is a solid material that is typically hard, opaque, shiny, and acts as good electrical and thermal conductivity.

 Types of Metal

There are two classifications of engineering metals. These are:

         i.            Ferrous Metals

       ii.            Non-Ferrous Metals

Ferrous Metals are metals that contain iron, therefore they are magnetic. Ferrous metals are very strong, but they corrode easily. Examples of ferrous metals are: alloy steel, stainless steel, cast iron, tool steel, pig iron and wrought iron.

Non-ferrous Metals are metals that do not contain iron, so they are not magnetic. Non-ferrous irons have lower strength but higher ability to resist corrosion. Non-ferrous metals are attractive in colour. Examples of non-ferrous metals are: copper, brass, aluminium, zinc, bronze and lead. 

Properties of metal:

Class Activity:

Question: Explain the following properties of metal:

1.      Density:

2.      Fusibility:

3.      Magnetic Property:

4.      Ductility:

5.      Conductivity of Heat:

6.      Brittleness:

7.      Tenacity:

8.      Sound Test:

9.      Colour or Lustre:

10.  Toughness:

Metal Processing

Metals are obtained from iron ore, which is dug from the ground. Metals are extracted from the iron ore through a process of smelting in a special equipment called Furnace.

A furnace is a device where metals can be heated to a certain temperature.

Examples of furnace:

1.      Electric Furnace: used for producing other grades of metal and steel.

2.      Blast Furnace: used for producing pig iron.

3.      Reverberating Furnace: used for producing non-ferrous metals

4.      Open-heart Furnace: used for producing special steel, stainless steel

5.      Bessemer Converter: used for producing other grades of metal or steel.

Class Activity:  (a) Describe the following metals:

1.      Iron ore:

2.      Pig iron:

3.      Cast Iron:

4.      Alloy

(b) mention the uses of the following examples of metals:

S/No	Metal	Uses
1	Mild steel
2	Wrought iron
3	Cast iron
4	Aluminium
5	Bell metal
6	Lead

(c) complete the following equations:

                                 i.            Copper  +  _______________ = Brass

                               ii.            Copper  + ________________ = Pewter

                              iii.            Phosphorous +  Tin  +  ________________= Bronze

Exercises:

1.      What is a metal?

2.      State two categories of metals,

3.      List  three examples of each of the major categories of metals

4.      What is Metal Processing?

5.      Describe a furnace.

6.      Mention 4 examples of furnace

Homework:

1.      Mention the names of 5 metals. 2.      State 5 uses of metals. 3.       What is an alloy?

IDENTIFICATION OF CERAMICS

CERAMICS are objects or products made of clay that has been heated to a very high temperature so that it becomes hard. Apart from clay, mud and cement can also be used to make ceramics.

Clay exists naturally in many parts of the world. When it is wet, it can easily be molded.  A POTTER is a person who moulds with clay. POTTERY is the art of using clay to make various objects.

Identification of materials used in manufacturing ceramics:

1.      CLAY:

Clay must be prepared before it is used in pottery. The process involved in making clay objects are as follows:

         i.            Moulding

       ii.            Firing

      iii.            Decoration

Some clay products are pots, flower vases, effigies and cooking utensils.

2.      CEMENT:

This is one of the ceramic materials for making concrete. It is regarded as ceramic because when mixed with water it can be made into different shapes and become very hard when dry. Some cement products are blocks, effigies and slate.

3.      GLASS:

This is made from sand, lime, soda and potash. It is not dug from the ground like clay and it can be shaped while soft and hardens on cooling. Some glass products are mirrors, bulbs, bottles, lenses and flask

Properties of Ceramics:

1.      They can break easily;

2.      They can withstand high temperature;

3.      Ceramics are less dense than most metals;

4.      They can be easily decorated;

5.      They are good electric insulators;

6.      They can withstand heavy compressive loads;

7.      They are not affected acids, water or oxygen.

Differences between ceramics and metals:

S/No	Ceramics	Metals
1	They are insulators. Electricity cannot pass through them.	They are good electricity conductors
2	They can break easily when dropped	They cannot break easily when dropped
3	When they are wet they can easily be moulded into various shapes and objects	Either when they are wet or dry they cannot be easily moulded into another shape
4	They can be mixed water to get soft	Water cannot soften them
5	They cannot be used for making bolts, nuts and screws	They can be used for making bolts, nuts and screws

Class exercise:

1.      What are ceramics?

2.      What is pottery?

3.      Who is a potter?

4.      What are the three materials for making cement?

5.      What is clay?

6.      What is cement?

7.      What are glasses?

8.      What are 5 properties of ceramics?

9.      What are 4 differences between ceramics and metals?

Research:

1.      What are plastics?

2.      What are the names of the two types of plastics?

3.      How can you describe the two types of plastics?

4.      What are the three methods of making plastics?

5.      What are 4 properties of plastics?

6.      What is rubber?

IDENTIFICATION OF PLASTICS AND RUBBER

Ø  PLASTICS

Plastics are obtained from petrol-chemical products and they are moulded to shape at a very high temperature. Plastics are non-metallic objects.

Types of plastics

1.      Thermoplastic: these are plastics that turn to liquid when heated and they can be remoulded. E.g cups, keg etc

2.      Thermoset: these are plastics that do not turn to liquid when heated and they cannot be remoulded. E.g shirt buttons, plastic handle of a cooking pot or knife, cases of radio, television or telephones.

Methods of making plastics

1.      Injection moulding: this is the process of making nylon and hair combs.

2.      Compression moulding: used for making thermoset objects, e.g Pressing Iron control knob.

3.      Extrusion: used for making pipes, tubes and rods.

4.      Calendaring: used for making buckets and cups.

Properties of Plastics

1.      Plastics are light in weight;

2.      plastics can crack easily;

3.      plastics can not rust;

4.      plastics can not withstand high temperature;

5.      plastics have high resistance to chemicals;

6.      plastics are electric insulators – current can not pass through them.

Ø  RUBBER

Rubber is an elastic material, which regains its original shape when stretched and released. Rubber is a non-metallic object.

Types of Rubber

There are two types of rubber, viz:

1.      Natural Rubber: this is the type of rubber which is obtained from a white substance called LATEX obtained from trees.

2.      Synthetic or Artificial Rubber:  this is the typoe of rubber which is obtained from petroleum products.

Methods of making Rubber products

1.      Vacuum forming;

2.      extrusion;

3.      compression moulding;

4.      calendaring

Properties of Rubber

1.      it is elastic;

2.      it is an insulator;

3.      it absorbs shock;

4.      it floats on water;

5.      it is light in weight.

Uses of Rubber

1.      it is used for making tyres;

2.      it is used for making catapult;

3.      it is used for making rain boots;

4.      it is used for making rubber sandals.

EXERCISES

1.      What is plastic?

2.      Mention the names of the two types of plastics.

3.      Briefly describe each of the two types of plastic.

4.      Describe the three methods of making plastics.

5.      Mention 4 properties of plastic.

6.      What is rubber?

7.      Describe 2 types of rubber.

8.      List 4 methods of making rubber products.

9.      State 4 properties of rubber.

10.  Mention 4 uses of rubber.

Research:

1.      List four properties of rubber.

2.      Mention four uses of rubber.

BOARD PRACTICE: Meaning, drawing instruments, care of instruments

Board Practice is an aspect of Technical Drawing that involves the process or method of drawing on the board with using the drawing instruments appropriately.

Technical Drawing is the drawing of an object with a combination of straight and curve lines to produce the imaginary image of the object ready for manufacture or reproduction

Technical Drawing Instruments:

1.      Drawing board

2.      Tee-square

3.      Set-square (30º - 60 º, 45 º angles)

4.      Pair of compasses

5.      A pair of dividers

6.      Protractors

7.      HB pencil

8.      2H pencil

9.      Eraser

10. Pencil sharpener

11. Templates

12. Scale rule

13. French curve

Board practice steps are:

Step 1: Place the drawing board conveniently on the table with the square edge to the left-hand side.

Step 2: place the drawing paper on the board leaving equal space all around.

Step 3: place the tee-square on the paper with the stock on the tee-square firmly against the edge of the drawing board on the left-hand side.

Step 4: slide the tee-square down gently without moving the paper.

Step 5: cut four pieces of paper-tapes to hold the paper in position and place them over the four corners if the paper.

The Title Block is usually at the bottom right-hand corner of the drawing paper and it is a piece of information, which enables others to understand what the drawing is about.

Such information entails the following:

1.      Name

2.      Subject

3.      Topic

4.      Class

5.      Date

Exercises:

1.      What is board practice?

2.      What is Technical Drawing?

3.      What are ten Technical drawing instruments?

4.      What steps can be followed during board practice?

5.      What is title block?

6.      What is the information that can be found on a title block?

Research:

1.      What is freehand sketching?

2.      Sketch a school bus.

Woodwork handtools: meaning, and marking out tools

As the name implies, Woodwork is a profession that involves the use of timber wood to make objects, furniture and buildings.  Examples of woodworkers are furniture makers and carpenters. A typical woodworker does most handy jobs in a workshop.

Definition:A workshop is a place where things are made or repaired.

The main item in a woodwork workshop is the WORKBENCH. A workbench is a bench on which various woodwork constructions are carried out. It is the major base for all woodwork constructions.

 

The centre of the bench is called a ‘WELL’. The function of the Well is to accommodate the tools brought from the tool cupboard to the bench top during operations. The well prevents tools from falling or rolling onto the floor.

The workbench has some appliances that are attached to it in order to carry out the construction of the woodwork.

Types and uses of workbench appliances:

1.      Vice:  this is fixed to the side of the bench. It is used for holding wood when working on it.

2.      Bench Stop: this is used to prevent wood from slipping off the bench top during planning.

 

3.      G-Clamp: this is a metal clamp which is in the form of letter ‘G’. it is used for holding small jobs to the bench while sawing and chiseling.

 

4.      F-Clamp: this is a metal clamp which is in form of letter ‘F’. it is used for holding small jobs to the bench while sawing. It has quick action adjustment.

5.      Sash Clamp:  this is a larger clamp. It is used for holding and drawing woods tight together when assembling or gluing works

 

Woodwork Measuring tools

Examples of measuring tools are:

1.       Metric rule: this is the simplest measuring tool in woodwork workshop. It comes as a metal, wood, plastic or coiled tape rule.

2.       Inside caliper: this is used for measuring the diameter of the inner part of a circular object.

 

3.       Outside caliper: this is used to measure the diameter of the outside part of a cylindrical bar.

4.       Odd-leg caliper: this is used to measure the centre of the round bars. In the odd-leg caliper one of its two legs is curved inward while the other leg is straight. This caliper is also known as Jenny’s caliper

 

5.       Pairs of dividers: this is used to measure the diameter of the outside part of a cylindrical bar.

 

Woodwork MarkingOut tools:

After taking measurements, the next step is to mark out the beginning and the end of the measured length. Examples of marking out tools are as follows:

1.        

Try-Square: this is used for marking lines that form a right angle.  It is also used to test the squareness of an edge.

 

2.        

Sliding Bevel: this is used for duplicating angles and for setting out bevels. The sliding bevel is similar to a try-square but its own blade is not fixed like the blade of try-square.

 

3.      

 Mitre Square: this is used to mark angles, particularly, angle 45°.

 

4.      

 Compass: this is used to mark the arcs of a circle

 

Exercises

1.       What is a workshop?

2.       Describe a workbench.

3.       What is the function of a well?

4.       Name and sketch 4 workbench appliances.

5.       List and sketch 4 measuring tools.

6.       List and sketch 4 marking out tools

Woodwork handtools: drilling and boring tools

Boring is the process of making holes into a timber or other objects.

Examples of some boring tools are:

1.      Wood brace

2.      Ratchet brace

3.      Bradawl

 

 

The RATCHET BRACE is an example of  boring tool which is used for boring holes in some hidden parts of a wooden material.  It has four parts, namely:

a.     The Head: this is made of hardwood and shaped to fit the hand of the user. It is screwed to a steel sleeve. It fits over the crank rod and runs on the hardened steel balls.

b.     The Crank: this is a rectangular bent metal rod. It fits into the hardwood or plastic handle

.

c.     The Chuck: this is the end of the crank which is enlarged, threaded and slotted to receive the socket and jaws respectively.

d.     The ratchet: this is a tool fitted to the ratchet brace so that holes can be drilled (bored) at specific parts that are not really exposed, such as corners where it is impossible to make complete turn.

Exercises:

1.      Describe the process of ‘boring’.

2.      List three boring tools.

3.      Draw and label a typical ratchet brace.

4.      Describe the four parts of a ratchet brace.

Woodwork handtools: holding and cutting tools

Holding Devices

Holding Devices are used to hold woods and metals firmly on a workbench or on a machine tool in order to have a successful operation on them.

Some holding devices are bench vice, bench hook, G-Clamp, Pliers, sash clamp and F-Clamp.

Vices

        I.           

 Bench Vice: this is used to hold wood and metal for filing, sawing, chiseling and tapping. They are fitted into the edge of the workbench by bolts and nuts. The jaw is tightened by rotating the bar.

      II.          

  Hand Vice: Unlike the bench vice, the hand vice is not fixed to anything. It is held by the hand. The work piece is put in between the two arms of the vice and it is tightened by means of a screw.

    III.          

  Machine Vice: the machine vice looks like a bench vice. However, it is not permanently fixed on the machine tool bed. It can be rotated for machining at any desired angle.

Pliers are work holding devices held in the hand of users. It is used for gripping and cutting wires and thin metal sheets. Pliers come in different forms. Some common pliers are:

 

        I.            Long nose pliers

      II.            Cutting pliers

    III.            Combination pliers

  IV.            Gripping pliers

Clamps are used to hold work piece at right angle while gluing and pining. Some clamps are:

        I.          

  Sash clamp: this is a large clamp used for holding and drawing parts of a work piece together while gluing.

      II.             

G-clamp: this is a metal clamp used for holding a work piece while sawing or chiseling. It looks like letter ‘G’

    III.         

  F-clamp: this is a metal clamp used for holding a work piece while sawing or chiseling. It looks like letter ‘F’

Some other holding devices are:

        I.          

  Bench Holdfast: this is used to hold job firmly on the bench when moulding and rebating

      II.             

Bench Hook: this is used to hold job to the bench while sawing or chiseling. It is also used to protect the bench.

Practical Class: Use of holding devices to hold timber jobs.

Exercises:

1.      What are holding devices used for?

2.      Mention 5 holding devices.

3.      Mention three types of vices.

4.      What are pliers?

5.      Mention four examples of pliers.

6.      List three examples of clamps.

7.      What is the function of a bench holdfast?

8.      What is the function of a bench hook?

Concept of Energy and Power

Energy is the ability of someone or something to do or produce work. Energy supplies power with which work is done.

Animals, including humans need energy to run, eat, play, jump, fly, push, pull and do other activities. Non-living things like wind need energy to sway tree branches and leaves. Fire needs energy to boil water. Without energy, birds can’t fly.

Work is done when a force is used to move somethingthrough a distance. The higher the amount of energy a body has the more work it can do.

Energy is measured in Joules, and the instrument for measuring energy is the Energy Metre.

Power is the rate at which work is done. Power is measured in Watts. The more the power the less the time taken to complete a work.

The symbol of energy is ‘E’ while the unit of energy is ‘JOULE’

Importance of energy

1.      It makes life possible. For instance, we know that there will be total darkness without light energy. The earth will be extremely cold without heat energy and we would not work with any tool without energy.

2.      Energy makes life more comfortable. We use gas cooker, refrigerators, fans and blenders to make our life more comfortable.

Forms of Energy

	Forms Of Energy	Sources
1	Potential energy	Objects on high platform
2	Nuclear energy	Atoms
3	Sound energy	Two objects hitting each other e.g. two metals
4	Heat energy	Hot objects, burning fuel substances,
5	Mechanical energy	Moving objects
6	Chemical energy	Fuel (charcoal, petrol etc) food
7	Light energy	Sun (solar), electric current
8	Electrical energy	Power Holding Company of Nigeria, electricity, generators, batteries

The two types of mechanical energy are potential and kinetic energy.

Sources of Energy

1.      Renewable Energy Source: this is an energy source which supplies energy continuously. E.g. the sun, river and wind.

2.      Non-Renewable Energy Source: this is an energy source which may dry up with time. E.g. petroleum, coal and gas.

Group work:

Define the following:

1.      Heat energy:

2.      Mechanical energy:

3.      Kinetic energy:

4.      Potential energy:

5.      Electrical energy:

6.      Chemical energy:

7.      Sound energy:

8.      Light/solar energy:

9.      Nuclear energy:

Exercises:

1.      What is energy?

2.      Define power?

3.      What is work?

4.      Mention 2 importance of energy.

5.      Describe the two sources of energy.

Concept of Energy and Power 2

Energy is the ability to do work.  The higher the amount of energy, the more work it can do. Energy is measured in joules.

Work is done when a force is used to move an object through a distance.

Power is the rate at which work is done, and it is measured in watts. The more power, the less the time taken to complete a work.

Work

The force applied determines the amount of work done and the distance moved in the direction of the force.  So, Work (w) is then the product of force (f) and distance (d).

Hence, we say W = F x D

The unit of force is Newton (N) while distance is measured in meters (m). Work is then measured in Newton meters (Nm) which is also called joule (j).

Example: Calculate the work done when a force of 10N moves a body through a distance of 20m

Solution:

Work                          =          force   x   distance

                                    =          10N x  20m

                                    =          200Nm (or 200joules)

Power

Power is the rate at which work is done. Power is determined by the work done and the time taken to do it.  It can be expressed as shown below:

Power (P) =              Work done

Time take to do the work

How energy, power and work are related.

Energy is required to do work. That is the reason why work and energy have the same unit.

Example: Bode pushes a load of mass 10kg to a distance of 30 meters in 20 seconds. Calculate:

a.     The work done

b.     The energy used

c.     Bode’s power  (g = 10 m/s²)

Solution:

a.     Work done   = force x distance

Remember that,

Force = mass x g = 10 x 10 = 100N

So, workdone = 100N x 30m = 2,000  joules

b.     Energy needed = work done

Therefore energy =  2,000  joules

c.     Power (P)     =                      Work done

Time take to do the work

                        = 2000

                             20

                        = 200 watts

EXERCISES:

1.      What is energy?

2.      Define power?

3.      What is work?

4.      Mention 2 importance of energy.

5.      Describe the sources of energy.

6.      Calculate the work done when a force of 50N moves a body through a distance of 30m.

7.      Sunmisola pushes a load of mass 10kg to a distance of 30 meters in 20 seconds. Calculate:

a.     The work done

b.     The energy used

c.     Sunmisola’s power  (g = 10 m/s²)