Energy – the one constant in the Universe!
Madhuri Katti
If one is asked to state a universal law of Nature that is crucial to our existence it would inevitably be the one which is the easiest to recall and has a connect with our daily lives – the Law of Conservation of Energy that states ‘Energy cannot be created, nor can it be destroyed but it can be transformed from one form to another. Total energy in the universe remains constant.’
It feels surreal to imagine that the energy that was created at the beginning of the universe approximately 13 billion years ago led to matter being formed and further led to the formation of multitude of galaxies, stars, planetary systems, black holes and various celestial bodies including our own solar system and planet Earth that sustains life. The same energy is being constantly recycled in the dynamic universe we live in.
As simple and easy as it may seem, energy is one of the most intriguing abstract concepts to comprehend and teach at different class levels. It is best taught with examples and activities. Research has shown that a multidisciplinary approach is the best to teach energy.
Historical context
Energy is ingrained in our very being. It is not an observable and measurable quantity like the mass or density of an object, but it is a physical quantity that connects all of us. The best way to introduce the topic is the enquiry-based learning approach. The five ‘W’s and one ‘H’ – Where, When, Why, What, Who and How? can be used to begin the lesson. Since middle school students are in the early stages of learning, the method of investigation and enquiry will set them on the path of lifelong learning.
Simple questions like, ‘Where do we get our energy from?’ or ‘What is the primary source of energy for planet Earth?’, ‘If you push an object, it moves – why does this happen?’ or ‘Why do our cell-phone batteries need recharging?’ or ‘What will happen if we don’t charge our phones?’ or ‘How can our muscle energy be connected to the Sun?’ or ‘Which is the first invention which made man’s work easy?’ can lead to an engaging introductory interaction on the topic. The answer to the last of these questions, invariably is either ‘fire’ or ‘the wheel’. ‘Fire’ is directly connected to combustion, chemical and heat energy, whereas wheel can be easily connected to one of the core concepts of energy – energy due to motion of the objects, i.e., the kinetic energy.
This introductory interaction can be extended to identify different forms of energy that we see all around us – heat energy, light energy, mechanical energy, chemical energy, sound energy, magnetic and electric energy and nuclear energy to make students reflect that energy is something that is omnipresent in our lives yet cannot be seen directly. One can see effects of energy change and energy conversion all around us.
Science
Energy is a common thread that connects all basic and applied sciences. In physics – the middle school curriculum objectives are to comprehend the concepts of force, work and energy, different forms and types of energy, sources of energy, transfer and conversion of energy from one form to another. Whereas in chemistry and biology, the context is more about the process by which energy is created – combustion, photosynthesis and uses of energy.
Physics
Energy is defined as the capacity to do work. But what is this work? The concept of work being a product of force and displacement can be easily demonstrated through simple activities such as pushing an object on a plane surface – the object will move in the direction of the force applied or a ball being thrown up – in this case force is in the upward direction so displacement too is in the upward direction. Work is said to be done if the applied force results in the displacement of the object in the direction of the force. This concept is subtly different to the common usage of the word ‘work’ in daily life. This difference usually triggers the curiosity of the learners. Sitting or standing at one place with a huge load no longer qualifies as work according to physics but we are burning some of our calories by holding things!
Once the concept of work is understood, it becomes easy to talk about energy as the capacity to do work. This equivalence of work and energy is a core concept of physics. Both are measured in terms of ‘Joules’ – SI unit of energy/work, ‘calorie’ being the other commonly used term for measuring energy.
While discussing and demonstrating different forms of energy, there is ample scope to show examples from everyday life. Simple demonstrations can be done using toys – wind-up toys/cars, bow and arrow and objects like battery operated remotes, light bulbs, even balcony plants. Every living or non-living object, including you and I, has stored internal energy due to the constant vibrating motion of molecules. To discuss forms of mechanical energy, i.e., stored energy, a simple stretching and releasing of a rubber band is an excellent activity.
Activity: The facilitator can arrange identical rubber bands and rulers for all students. Students are asked to stretch the rubber band to a specified length using a ruler and release it from a marked position. Students will then note how far the rubber band travels. Then they are asked to stretch more and see how far the rubber bands fly. Through this activity students can correlate how the amount of stretching is related to the distance that the rubber band travels. They can do a simple worksheet based on the activity with questions like what caused the motion of the rubber band? What kind of energy is stored in a rubber band? They can thus observe and understand how the stored potential energy of the rubber band changes into kinetic energy once it is released. They can also note that a stretched rubber band becomes a little warm. What kind of energy change is happening here?
The most common demonstrations of mechanical energy are the simple pendulum and an object being thrown up. A fun demonstration is using toys – windup a toy car or a roller coaster kit/hot wheels kit. They can also be asked to design a moving toy car using a balloon. There are numerous DIY activities available online. Here is one simple method.
Activity
Toy Car Balloon Racers
Requirements: Toy car, balloon, plastic straw (thick straw), rubber band, tape and balloon pump (if available)
Method
Step 1: Cut the straw and insert it into the neck of the balloon and secure it with a rubber band as shown.
Step 2: Tape the balloon and straw to the top of the toy car with the straw pointing towards the back of the car.
Step 3: Blow through the straw or use the balloon pump to inflate the balloon. Keep the end of the straw closed so that the balloon remains inflated.
Observation
Set the car on a smooth surface and release the straw. The toy car will simply zoom away!
The inflated balloon has stored elastic energy, the air rushing out creates a force in the backward direction, moving the car forward. This is a simple demonstration of forces, potential and kinetic energy!
The other hands-on demonstration that can be assigned is the DIY DC motor activity from Arvind Gupta toys from trash website using a coil of wire, magnets and battery.
What you will need
Copper wire (1.5 meter, enamelled copper wire), battery (1.5 V), disk magnets, safety pins, bicycle rubber bands.
Method
Step 1: Wind copper wire on a battery cell (10-15 turns). Remove the coil and tie the coil ends outwards.
Step 2: Scrape the enamel insulation from both ends as shown.
Step 3: Fasten the disk magnet on the battery using rubber bands. Stick safety pins to the ends of the battery.
Step 4: Place the coil between the loops and watch the rotation of the coil. You can use other magnets to see how it influences the direction of the rotation.
This simple elegant demonstration shows how chemical and electrical energy of the battery and magnetic energy is used to create mechanical motion. We all know motors are indispensable in all the appliances that we use, such as fans, washing machines, mixer-grinders, etc.
Chemistry and biology: To understand the other most basic form of energy – chemical energy – there is a need to digress into chemistry and biology. If we burn dry wood, it releases heat and light energy. This is the basic combustion process. But what actually happens during combustion? Substances burn in the presence of oxygen, releasing both heat and light energies. The molecular bonds of combustible materials store energy and once they are broken, they release energy. The most basic phenomena like photosynthesis is a complex process of light energy of the Sun being transformed into stored chemical energy. Whereas the most complex nuclear reactions – nuclear fission – can be simply understood as the breaking of strong nuclear bonds that hold nucleons together in an atom releasing tremendous heat energy in the process. Nuclear force – is one of strongest forces of attraction of the four basic forces of the nature, hence when nuclear force of attraction is overcome, splitting an atom into two, it leads to a huge release of energy.
The process of photosynthesis is the most primary energy conversion process where the Sun’s energy gets converted into chemical energy or food energy. This is the primary source of sustenance of life on our planet. Other biological processes like respiration or pumping of blood in the heart can also be viewed from a physics perspective.
It should be made clear to the students that every natural phenomenon can be seen from the perspective of different disciplines but to get a holistic idea of how these processes occur, one must learn to integrate understanding acquired from different subjects.
Art and mythology
Early evidence of humans being intrigued by the Sun can be found in art and mythology. The Sun figures as a god in the mythological tales of every land. People worshipped the Sun, referring to it as a ball of fire and also understood its importance in the cosmic order of things. Ancient tribal art depicts the Sun as a circle with rays of light emanating from it. In some, the rays are like waves and in others, simple straight rays all diverging out from the Sun.
Almost all mythologies across religion and creed have gods for their five basic elements – Sun, air, water, fire and wind. And all of these are discussed when we talk of energy or energy transfer in modern times.
The most famous paintings of Van Gogh – Sunflowers or Starry Night can be easily integrated while teaching that the Sun and stars are a storehouse of energy in the universe. Sunflower plants or any plants thrive on sunlight. Throughout the day, sunlight pervades on parts of Earth facing the Sun, almost blinding us. Only at night do we see numerous stars. All stars make energy from a simple fusion process – fusing of hydrogen atoms into helium, while releasing tremendous light and heat energy. The light from those far away twinkling stars take light years to reach us hence enabling us to see them at night and thus inspiring art, rhymes, literature and different forms of creativity.
History
The progress of human civilization is documented by history. If this progress is viewed as a grand timeline, then all benchmarks on it are not just about kingdoms, great wars, colonization conflicts – they are also about technological progress with time. The early wars were fought with bows and arrows and spears and today we have countries using nuclear weapons as deterrents. All great inventions have led to corresponding changes in the societal structure and world economy. What is the core motivation for all these inventions? To make human life easy and to comprehend the universe. Humans are intelligent and curious beings. Most inventions are an innovation in energy transfer to make everyday existence easy. Students learn about the Egyptian civilization – they learn about different clocks, inclined planes, sun dials. All of these can be connected to the concept of energy. If they are learning about industrial revolution – we can connect the steam engine to the idea of change of heat energy into mechanical energy or we can discuss how Michael Faraday’s law of electromagnetic induction – the theory that enabled conversion of mechanical energy into electrical energy which led to electrification of the world!
History provides us with a way of looking at technological progress chronologically. The power of nuclear energy was enough to end the Second World War horrifically and tragically. It demonstrated the power of the nucleus of a heavy atom!
Different sources of energy and energy transfer processes can be taught interestingly with this context of history. The recent Nobel Prize awarded to the development of the lithium-ion battery which can be used in everything from mobile phones to laptops and electric vehicles can also be an excellent example of how technological progress happens. Making lessons relevant by relating them to the latest findings makes even an abstract topic highly interesting.
Global perspective: energy crisis
A socio-scientific perspective on energy sources, use and distribution of energy, depletion and effects of fossil fuels are crucial to the understanding of energy. In middle school, students get an overview of different energy resources, power plants and how electricity that is crucial for our daily existence is produced. They learn about different kinds of renewable and non-renewable energy resources. The best way to teach these theoretical aspects is through group presentation or peer-teaching or mini-class debates. Different groups can be assigned to explore and make presentations on assigned energy resources, how useful energy is produced, what are the advantages and disadvantages of the energy resources, etc. After their presentations, there can be a follow-up debate about renewable versus non-renewable energy resource. This method covers all kinds of energy resources extensively and through research, presentation and debate students also become pro-active learners. They also connect to the global energy crisis, climate change and learn about sustainable development goals of the UN to protect the planet.
Health, fitness and energy
The human body is a storehouse of energy which is needed for all physiological processes and activities. A simple poster or chart listing calorie content in different food items, daily calorie needs and how many calories are burnt in daily activities will go a long way in creating health awareness. Students can research and make their own nutritious diet chart. They can also make a poster about calorie content of junk food and its effect on health!
Conclusion
Energy is a concept that can help students not only to connect the dots between the different topics in physics (mechanics, heat, light, sound, electricity, etc.) but also to link different disciplines – right from human life, daily needs gadgets to celestial events on a grand cosmological scale or history and even art!
The energy crisis has become most relevant and contentious over the past few decades due to depletion of non-renewable energy resources. Saving electricity is the need of the day. Students can use this knowledge to create awareness about how our civilization and planet is in peril.
Middle school is the best time to inculcate the right scientific attitude and values through integrated teaching methods using curated hands-on activities, teaching resources, audio-visual aids and simulations available online.
I would like to end with the famous Nikola Tesla quote: “If you want to find the secrets of the universe think in terms of energy, frequency and vibration.”
References
- Science Buddies Staff. (2020, June 23). Rubber Bands for Energy. Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/ApMech_p017/mechanical-engineering/rubber-bands-for-energy
- https://www.researchgate.net/publication/331112490_Interdisciplinary_Approach-Based_Energy_Education/link/5c665a1b299bf1d14cc7710e/download
- http://www.arvindguptatoys.com/toys/motor.html
- https://www.bbc.co.uk/bitesize/guides/zyfgr82/revision/1
- https://www.makeandtakes.com/toy-car-balloon-racers
The author teaches physics at Modern High School for Girls, Kolkata. She also freelances for Live History India. She has a keen interest in photography, history of science and astronomy. She can be reached at madkat70@gmail.com and madhuri.vithalkatti@mhsforgirls.edu.in.
