THE ESSENCE OF CHANGE CHAPTER ,energy,conversion,life is easy,laws of physics

The essence of change,law, energy, conversion

1. THE ESSENCE OF CHANGE BY DR.SREEREMYA DIRECT LEARNING CLASS 6 STATE

2. DIFFERENT ACTIVITIES ARE TRACTOR MOVING JEEP MOVING LOUD SPEAKER ON FARMER WORKING IN FARMLAND DUCKS SWIMMING MOTOR CONNECTED FROM WATER BODY TO FARM LAND CHILDREN PLAYING ETC Observe the picture. Don't you see the lush green field, the road,the house,etc .?(PREVIOUS SLIDE)

3. E nergy for the movement is obtained from the food we eat ( eg - From picture-children playing with ball). Energy is required for doing other kinds of work as well MOVEMENT IS BASED ON THE ENERGY The sunlight enables us to see everything during daytime. You know that light is a form of energy. Energy for everything

4. The light produced using electricity helps us during night time . Heat is used for cooking food. Electrical energy is used to make a fan work. Energy for everything

5. Context Form of energy used Riding motor Vehicles Energy from fuels. Drying clothes HEAT ENERGY TO DRY THE CLOTHES D ifferent forms of energy

6. Context Form of energy used Bulbs glowing An electric bulb uses electrical energy and transforms it mainly into light and heat energy. Loudspeakers working Electrical energy into sound energy. Different forms of energy

7. Heat, electricity, light, sound etc., are different forms of energy. Is light energy the only form of energy produced when a bulb glows. Switch off a bulb after keeping it on for some time. Feel the glass surface of the bulb carefully, with your finger-YOU FEEL YOUR HANDS ARE HEAT WHEN YOU TOUCH BULBS SURFACE FORMS OF ENERGY

8. An electric bulb uses electrical energy and transforms it mainly into light and heat energy O ther situations in which more than one form of energy is produced- Grinder is connected to main source show that the electrical energy is converted into mechanical, heat, noise and light energy Different forms of energy

9. Situation Forms of energy Form of energy we produced make use of A torch is lit chemical energy stored in batteries is converted into electrical energy –then to light and heat energy Fire wood is burning in an oven chemical energy into kinetic energy (Moving molecules)in the form of HEAT HEAT ENERGY An electric bulb is lit electrical energy It is converted to heat and light energy A candle is burning it requires a chemical reaction to burn a candle heat and light A cracker is bursting So the chemical energy stored in the firecracker It is converted into light, sound, and heat energy IDENTIFYING THE DIFFERENT FORMS OF ENERGY PRODUCED IN EACH CASE AND THE ONE WE USUALLY MAKE USE OF.

10. In the case of burning wood, stored potential energy (in the form of chemical energy) in the log is released due to heating by other excited atoms. This chemical reaction is called combustion and requires oxygen. Combustion changes the potential chemical energy into kinetic energy in the form of heat. Forms of energy

11. When a sparkler is lit Which are the forms of energy produced in the following situations? So the chemical energy stored in the firecracker It is converted into light, sound, and heat energy

12. While riding a motorcycle- muscular energy was fromed from the rider and the machenical energy from the bike FORMS OF ENERGY While operating an electric motor-An electric motor converts electrical energy into mechanical energy   PROCESS IN DETAIL- An electric motor converts electrical energy into mechanical energy   through the procedure of electromagnetic induction. So therefore we link the electric motor to a circuit to run its shaft and we get the preferred output as the rotation of the shaft provides mechanical kinetic energy.

13. Mechanical Energy Electrical energy or the energy produced by burning fuels is used to make an engine work and, in turn , to make machine parts move . Working of an engine involves mechanical energy which enables vehicles move. Energy can be transformed from one form to another

14. CHEMICAL ENERGY

15. The energy contained in a substance is chemical energy . Plants convert solar energy into chemical energy through photosynthesis. Chemical energy thus stored up, reaches animals through food. While burning fire wood too , we get the chemical energy stored up in plants . All substances contain chemical energy. CHEMICAL ENERGY

16. How do vehicles that run on petrol and diesel depend on the sun for energy????? All the energy in oil, gas, and coal originally came from the sun, captured through photosynthesis. In the same way that we burn wood to release energy that trees capture from the sun, we burn fossil fuels to release the energy that ancient plants captured from the sun . SUN PLANTS FOSSIL FUEL FORMS OF ENERGY TO OIL,GAS,COAL,NATURAL GAS, LPG

17. Fossil fuel is a generic term for non-renewable energy sources such as coal, coal products, natural gas, derived gas, crude oil, petroleum products and non-renewable wastes. These fuels originate from plants and animals that existed in the geological past (for example, millions of years ago ). FOSSIL FUEL

18. Listening to the news on a radio A radio first converts electrical energy into sound energy. It receive EM(ELECTROMAGENTIC) waves from air that being send through air by a radio transmitter. the radio receive these signals and uses RF amplification and detector which convert it to electrical signals and then finally uses audio amplifier which provide us melodious sound. To make the maximum use of energy, energy loss in appliances should be minimised . How many changes!

19. Uses of an Electric Generator They provide the power for most power networks across cities Small scale generators provide a good backup for household power needs or small businesses At construction sites, before the power is set up, they extensively make use of electric generators Energy-efficient as fuel consumption is reduced drastically Since they give a range of voltage output, they are used in labs They are used to drive motors They are used in transportation VARIOUS ACTIVITES AND USES OF GENERATOR

20. A B C Which situation in the given picture does not use light energy?B In which situation is sound energy produced?B In which situation is heat energy made use of?A FORMS OF ENERGY

21. Try doing the experiment given below and write down your observations. Take some ice cubes in a beaker and heat it as shown in the figure When the ice melts to change to water at 0oC temperature,  heat energy is converted to the latent energy. As ice absorbs heat from surrounding When ice melts

22. When heat energy is supplied to ice it changes into water and then to vapour . If we cool the steam it gets converted into water and further cooling of water changes into ice. Here the heat energy is used up in changing the state of matter. the heat is used to increase the kinetic energy of the particles of ice to such an extent that they break away from the rigid lattice structure of the solid form, ice, and move around freely to form the liquid form, water. So, until all the ice has melted, the heat absorbed does not raise the temperature of the ice-water mixture. This heat, which does not raise the temperature of the body, is called Latent Heat. WHEN IC MELTS

23. Ice absorbs heat energy and changes into water, its liquid state. Water further absorbs heat energy and gets converted into steam. When steam loses heat energy it again changes into water. When heat energy is further lost, the water, in turn, gets changed into ice. When ice melts

24. Substances undergo change of state when they absorb or release adequate heat energy. On absorbing heat energy, they change from the solid state to the liquid state and then to the gaseous state . Substances get converted from the gaseous state to the liquid state and then to the solid state by releasing heat energy. Change of state

25. ICE CUBE Change of state ABSORBS HEAT CHANGE INTO WATER WATER ABSORBS HEAT STEAM RELEASES HEAT WATER FURTHER LOST WATER

26. V aporization , conversion of a substance from the liquid or solid phase into the gaseous (vapour) phase. If conditions allow the formation of vapour bubbles within a liquid, the vaporization process is called boiling. Direct conversion from solid to vapour is called sublimation. Vaporization

27. Condensation is the process through which the physical state of matter changes from the gaseous phase into the liquid phase. For example, condensation occurs when water vapour (gaseous form) in the air changes into liquid water when it comes in contact with a cooler surface. Condensation

28. Is energy absorbed or released when steam is changed into water? Since, during phase change from gas to liquid, energy has to be decreased, i.e. energy is released. When steam condenses into water it gains heat energy. WHEN ICE MELTS

29. When water is heated to a temperature X, it gets converted into steam at temperature X by a process called R. And when steam at temperature X is cooled, it reconverted into the water at the same temperature X by a process called S. (a) How much is the value of X in Kelvin? (b) What is the process R called? (c) What is the name of the energy absorbed during the process R? (d) What is process S known as? (e) What is the name of energy released during the process S known as? Solution (a) 373 Kelvin The boiling point of water is  100∘ C, that is 100 + 273 = 373K (b) Vaporisation (c) Latent heat of Vaporisation (d) Condensation (e) Latent heat of condensation (negative value of vaporization) FOR WORK OUT

30. It is the change of state that gave us these beautiful shapes??YES

31. Situation Change taking place in state or in shape Heating solid ghee melts Cutting vegetables becomes smaller pieces Heating a PVC pipe expands Heating wax melts Tearing paper becomes smaller pieces Breaking a bottle becomes smaller pieces Heating ICE(NOTE-IN TEXTBOOK IT IS LAC CORRECT IT TO ICE) melts Crumpling paper changes shape CHANGE OF STATES

32. Change in the physical properties such as state, shape or size is termed as physical change. Expansion, melting, breaking, tearing etc., are all physical changes . New substances are not formed during physical changes. Physical change

33. Take some sugar in a spoon and heat until it melts.TASTE IT-IT TASTES DIFFERENT FROM SUGAR Heat again. Do you observe a change in the colour?YES TASTE IT?BITTER Permanent change

34. The burning of sugar is a permanent chemical change. A change in which the chemical composition of a substance changes and a new substance is formed is known as chemical change. For example, curdling of milk, and rusting of iron. The burning of sugar leads to a reaction of sugar with oxygen in the air and leads to the formation of carbon dioxide and water. This change is irreversible and can not be turned back to their respective reactants . B urning of sugar is a temporary change. SUGAR WHEN BURNED

35. EXPERIMENT-BURN MAGNESIUM RIBBON

36. EXPERIMENT-BURN MAGNESIUM RIBBON Burn a piece of paper When magnesium ribbon burns in presence of oxygen. We could observe a dazzling white flame and a white substance named magnesium oxide It produces carbon dioxide and ash is left behind. It is a chemical change

37. The process in which substances change into new substances by absorbing or releasing energy is termed a chemical change. Chemical change is a permanent change . Different types of chemical changes A large number of chemical changes take place everyday in the human body as well as in nature . cooked rice tastes sweet when chewed for some time. the colour of the film changes while taking X-rays. the colour of clothes fades when exposed to sunlight. iron rods rust. mangoes ripen. Chemical change

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