MEANING AND NATURE OF TECHNOLOGY (ITE 201) Dr. Gambari, A. Isiaka E-mail: [email protected] Website: www.gambariisiaka.com Blogsite: www.drgambari.com A Lecture Presented at University of Ilorin for Undergraduate Students of Educational Technology Department. 11 st November, 2013
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MEANING AND NATURE OF TECHNOLOGY (ITE 201)
MEANING AND NATURE OF TECHNOLOGY (ITE 201)
Dr. Gambari, A. IsiakaE-mail: [email protected]: www.gambariisiaka.com
Blogsite: www.drgambari.com
A Lecture Presented at University of Ilorin for Undergraduate Students of Educational Technology Department.
11st November, 2013
Objectives
Meaning of Energy Different kinds of energy Classification of Energy How Energy can be changed from one form to
into another. First and second laws of thermodynamics that
summarise what happens during energy changes.
Examine some of the ways that energy is harnessed in the modern world
Explain heat exchangers, heat pumps and air conditioners, the internal combustion engine (the engine in a car or truck), the electric motor and the power stations that generate electricity for our homes and factories. Sources of energy
WHAT IS ENERGY?
Scientists define energy as the capacity to do ‘work’.
In science, work refers to almost anything that can be done!
The children are using their energy to dance.
Cont…
the musician is using her energy to sing and play the base.
The energy of the waterfall makes the water move fast,
the energy of the train enables it to pull a heavy load at high speed.
Cont…
Anything that gets moving, or makes noise or heat or light or electricity, is using energy and doing work.
The energy is not the same thing as the work that is done; energy is simply the ability or readiness to do work.
DIFFERENT KINDS OF ENERGY
mechanical energy (that is the energy associated with the mass of an object),
electrical energy, sound energy, light energy, heat energy, chemical energy, and nuclear energy.
Mechanical Energy
Forms of energy that involve motion are classified as kinetic energy and
forms of energy that do not involve motion are classified as potential energy.
Kinetic Energy
Kinetic energy is the energy of moving things.
‘Kinetic’ comes from the Greek word ‘kinesis’ meaning motion.
The term kinetic energy is used mainly for the mechanical energy of a moving object.
However electricity, sound, light and heat all involve motion, so they are often regarded as forms of kinetic energy too. Gambari 2012 8
Flywheel at a pumping station
Cont…
Mechanical kinetic energy is the energy of anything that moves and has mass.
Kinetic energy is associated with all kinds of motion, including rotation.
Electrical Energy
Electrical energy is a stream of electrons flowing through a conductor.
Electricity is a convenient form of energy because it can be delivered to homes and factories through wires, and it can easily be converted into other kinds of energy.
Sound Energy
Sound energy is a pulse of vibrations travelling through the air,
The source of the sound vibrates and nudges the molecules in the air surrounding it.
You can easily feel the vibrations from a loudspeaker like the one shown on the right.
A pulse of backwards-and-forwards vibrations of the air molecules carries the sound energy through the air at a speed of about 330 metres per second.
Light Energy
Light energy is an example of electromagnetic radiation. Electromagnetic radiation includes radio and TV waves, heat (infra-red) rays, light, X-rays and γ-rays. These rays all carry energy, but unlike sound waves (which must be carried by a medium such as air or water), they require no medium. They travel through space at a speed of 3 x 109 metres per second.
light which provides energy for life on Earth through photosynthesis.
Heat Energy
Heat energy is part of the electromagnetic radiation that we receive from the sun. We also get heat energy from burning fuels and in other ways.
Cont…
Heat is a low grade form of energy because a lot of it is always wasted as internal kinetic energy and therefore cannot do useful work.
Potential Energy
Potential energy is stored energy, or energy-in-waiting.
‘Potential’ comes from the Latin word ‘potentia’ meaning power or capability.
The term potential energy is used mainly for the stored mechanical energy of a stationary object which is being acted on by a force. However, chemical and nuclear energy are also forms of stored energy.
Cont…
Mechanical potential energy is the stored energy of a stationary object that is being acted on by a force; an object that is poised, ready to move.
A large rock is balanced high up on a cliff. It is being pulled down by the force of gravity but is supported by the rocks underneath it. If this rock slips, or if someone pushes it, it will crash down and damage anything that it hits.
Cont…
Any object above ground level has potential energy of this sort.
The arrow is being pushed forward by the tension in the bowstring. When the archer lets go of the bowstring, it will shoot the arrow through the air towards its target.
Any stationary object that is being pushed or pulled by a piece of elastic, or a spring, has potential energy of this sort.
Chemical Energy
Chemical energy is the potential energy that is stored in substances that are ready to undergo chemical reactions.
A good example is an electric cell or battery.
When the terminals are connected and the circuit is switched on, chemical reactions in the cell will send a stream of electrons through the circuit to do their work.
Cont…
Other examples of chemical potential energy are explosives and fuels, including food which is the fuel for our bodies.
Nuclear Energy
Nuclear energy is the potential energy that is stored in the nuclei of atoms.
This energy is released slowly during radio-active decay and fast during nuclear fission and nuclear fusion.
Nuclear fission is the source of energy in nuclear power stations and atom bombs, and nuclear fusion is the source of energy of the stars including our sun.
CHANGING ONE KIND OF ENERGY INTO ANOTHER CHANGING ONE KIND OF ENERGY INTO ANOTHER
Gambari 2012
Explosions
Explosions: The head of a match contains stored chemical energy. When we strike the match, the match head explodes (gently) and its chemical energy changes into heat and light energy. chemical energy > heat (and light) energy
Industrial explosives such as dynamite contain a large amount of stored chemical energy. When dynamite is used to break rocks in a quarry or a mine, the chemical energy changes into kinetic energy as the rocks fly apart; the explosion makes a lot of heat and sound energy too! chemical energy > kinetic energy (plus heat and sound energy)
Battery
Using a cell or battery: An electric cell or battery contains stored chemical energy.
When a cell is connected to a light bulb, the stored chemical energy changes into electrical energy in the wires, and the electrical energy in the wires changes into light energy (and a bit of heat) in the bulb.
chemical energy > electrical energy > light (and heat) energy
Cont…
the chemical energy stored in the battery changes to electrical energy in the wires that lead to the small electric motor. The motor changes the electrical energy into mechanical kinetic energy in the form of a turning pulley wheel that drives a larger pulley wheel. The larger pulley wheel is attached to an axel and, as the axel turns, it winds up a string and lifts a mass. Lifting the mass changes kinetic energy from the motor into potential energy in the raised mass.
chemical energy > electrical energy > kinetic energy > potential energy
Dynamos
Using a dynamo: Many kinds of electric motor can convert energy in both directions. If an electric current flows through a motor of this kind, the axel of the motor turns; but if, alternatively, something makes the axel turn, then it produces an electric current! A motor that is used backwards like this, to make electricity, is called a dynamo.
Cont…
chemical energy (in the fuel) > heat energy (from the burning fuel) > kinetic energy (in the steam engine) > electrical energy (in the dynamo) > light energy (in the light bulb).
Cont…
potential energy (in the water because it is raised above the ground) > kinetic energy (in the flowing water which turns the paddle wheel) > electrical energy (in the dynamo and the wires) > light energy (in the light bulb).
Cont…
potential energy (in the coiled spring) > kinetic energy (as the spring uncurls and turns the pulley wheels) > electrical energy (in the dynamo) > light energy (in the light bulb).
Food
Using food: The energy that keeps us warm and keeps us moving, comes from the chemical energy stored in our food.
As they ride up the hill, they change the chemical energy stored in their food into kinetic energy in their legs and in the moving bicycles.
Cont…
As they ride up the hill, they change the chemical energy stored in their food into kinetic energy in their legs and in the moving bicycles. As they climb higher and higher, some of this kinetic energy is gradually stored as potential energy. When they reach the top, they no longer need to use energy from their food to push the pedals around.
The potential energy due to their height, gives them with all the energy they need to freewheel back to the bottom of the hill without pedalling! As they speed downhill, their potential energy is converted back into kinetic energy.
The making of food and fuels
Plants are the producers at the start of all food chains. In the process called photosynthesis.
they use light energy from the sun to make carbohydrates from carbon dioxide (in the air) and water (in the soil). After that, some of the carbohydrates are converted into lipids and proteins. In the end, all our food and all our fossil fuels come from plants.
light energy (from sun) > chemical energy (stored in food) > kinetic energy (legs moving and bicycle moving uphill) > potential energy (stored as height) > kinetic energy (bicycle freewheeling downhill).
Energy Changes
1woman firing a gun, and the cartridge that was loaded into the gun
Energy changes
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