00:00 Who do everyone?

00:12 My name is Tabelo A.A. the official teacher for today.

00:15 The topic we are examining today is energy transformation and power.

00:20 Before the commencement of the lesson, we will talk about the lesson objectives.

00:24 At the end of the lesson, the students should be able to one briefly explain energy transformation.

00:31 Two, states the laws of conservation of energy, three, distinguish between renewable and non-renewable energy.

00:39 Four, advantages and disadvantages of renewable energy, five, defined power and states is formula.

00:47 And lastly, six, solve simple problems or nets, energy transformation.

00:52 Energy transformation is defined at the process of changing energy from one form to another,

00:59 just like we said earlier on the mechanical energy.

01:03 We have potential energy, it's been converted to kinetic energy.

01:08 There are different kinds of energy that can be transformed from one form to another.

01:14 Examples are chemical energy can be converted to electrical energy,

01:19 just like we are in battery or cell to produce lights.

01:23 Also, mechanical energy can be converted to electric car energy,

01:29 just like what we have in our dynamo to generate power.

01:32 Also, solar energy can also be used or be converted or transformed to produce electric energy.

01:41 For mechanical energy, potential energy can be converted to kinetic energy

01:47 and vice versa, that is kinetic energy can also be converted to potential energy.

01:54 When an object is hit at the vertical height, H, if this is an object,

02:02 and this is the vertical height, from here to here is our H.

02:10 The objects are the maximum height processes, maximum potential energy,

02:16 and at this point, if the potential energy is maximum,

02:23 the kinetic energy equals zero, because the object is not moving.

02:30 Based on our definition from the last class,

02:34 potential energy is the energy due to a position of an object,

02:38 why kinetic energy is the energy processed by a body by a vessel of its motion.

02:43 At this point, the objects are stressed, they possess the maximum potential energy.

02:49 It is not moving, so that means the kinetic energy is zero.

02:54 Now, if the object is released from the height H,

02:59 that is the object here is released from height H,

03:02 the potential energy decreases, that is, as the object is falling,

03:08 the height is reducing, and as the height is reducing,

03:11 the potential energy is decreasing.

03:14 Why the object, as it is falling, is gaining momentum, the speed increases,

03:20 and like we said, our kinetic energy is a function of motion.

03:24 That means, as the object is falling, it is moving,

03:27 the kinetic energy is increasing.

03:30 In other words, as the potential energy is reducing,

03:33 the kinetic energy is increasing.

03:36 So, that is what we call, it's an example of what we call transformation of energy.

03:41 The kinetic energy is now being transformed into the potential energy,

03:48 it's now being transformed into kinetic energy.

03:52 At the midway,

03:57 the object possess equal kinetic and potential energy,

04:01 that is, the kinetic energy is equal to the potential energy made with,

04:07 that is the middle of the heights, but just before striking the ground,

04:13 all the potential energy will be completely converted to kinetic energy.

04:18 So, that before it strikes the ground,

04:21 it has a maximum velocity, so that means our kinetic energy is maximum,

04:26 and here, our potential energy will not be equal to zero.

04:32 So, that means, the maximum potential energy,

04:36 while the object is at risk,

04:37 has been fully converted to maximum kinetic energy,

04:42 before the object strikes the ground,

04:46 and the kinetic energy wishes zero,

04:50 and the maximum height has now increased,

04:53 and has been transformed to maximum kinetic energy,

04:57 before the object strikes the ground.

05:00 Example, a ball of mass,

05:04 it's ground, 4 from raised, from a 100 meter height,

05:09 neglecting air resistance calculated to the energy,

05:13 after falling a distance of 40 meter.

05:21 Now, from the question, our mass equals 8 kg.

05:28 Why the heights, H equals 100 meter?

05:37 Neglety air resistance, we are to calculate the total energy,

05:41 after falling a distance of 40 meter.

05:44 Now, our formula for potential energy from the last classes,

05:49 mg-ish, where our g is a constant?

05:55 That is associated with gravity,

05:57 and value is 10 meter per seconds squared.

06:04 Now, at height 100,

06:07 the potential energy equals 8 multiplied by 10 multiplied by 10.

06:19 So, that means we have 8, 100, 8,000 joules.

06:32 That's the potential energy, where it is 100.

06:36 Now, as it is falling at height H equals 40 meter,

06:47 then, the potential energy, as at that point,

06:50 will not be equal to mg-ish,

06:53 and that is, the mass still remains the same on change.

06:57 It's multiplied by our constants,

07:00 which is associated to gravity with value 10,

07:04 and our height, as reduced to 40.

07:09 So, we have 3,200 joules.

07:14 That means at height 40, the energy has falling.

07:22 The potential energy has reduced,

07:27 and the kinetic energy has increased.

07:30 And at this point, the total energy,

07:35 if we are to calculate the kinetic energy,

07:38 we know that the total energy

07:42 equals the potential energy plus the kinetic energy.

07:48 At at 100, the total energy is 8,000 joules,

07:55 and that is equal to the potential energy,

07:59 at height 40, which is 30,200 plus the kinetic energy.

08:09 Now, if the total energy equals potential energy plus kinetic energy,

08:15 and at height 100, our potential energy is 8,000,

08:23 and when it is 40, we have a 30,200.

08:26 First, now, to know the kinetic energy,

08:28 it will now be 8,000 minus 30,200,

08:34 and that will be equal to our kinetic energy,

08:38 so that therefore, at the end of the day, our kinetic energy

08:42 will now be equal to 4,800 joules.

08:47 So, in other words, when the object falls to a height 40 meter,

08:54 the kinetic energy has increased.

08:58 Initially, at 100 is zero,

09:00 whereas it is falling, it has started increasing,

09:03 such that at height 40 meter is already 4,800,

09:09 why the potential energy, as I said at particular point,

09:12 is now 3,200.

09:15 So, at the end of the day, just before striking the ground,

09:20 the kinetic energy will become 8,000 joules,

09:24 and the potential energy will become zero.

09:27 So, that is transformation of energy from potential energy

09:31 to kinetic energy.

09:33 Another example.

09:35 At what height above the ground,

09:38 its mass of body, 15 kilogram,

09:41 be located to have a potential energy equal to kinetic energy,

09:46 possessed by another body of mass, 15 kilogram,

09:49 moving with a velocity of 10 meter per seconds.

09:59 Now, since the mass equals 15 kilogram,

10:06 and velocity equals 10 meter per seconds,

10:13 now, releasing potential energy to kinetic energy,

10:19 using the formula MGH equals half NV squared.

10:24 Now, 15 multiplied by 10 multiplied by H equals half multiplied

10:35 by 15 multiplied by 10 squared.

10:39 This is 150 multiplied by H equals half multiplied by 15 multiplied

10:54 by 100.

10:57 You have two multiplied by 150 multiplied

11:02 by H equals 1,500.

11:09 Therefore, our H equals 1,500

11:16 all over 3,500.

11:23 Therefore, our H equals 5 meter.

11:31 So, that is how to determine the height

11:33 at which the potential energy is equal to the kinetic energy.

11:40 Another example.

11:41 To address our discussion, a ball of mass 1.3 kilogram

11:47 is drawn from a height of 100 meter above the ground.

11:50 Calculate one potential energy before dropping it.

11:54 Two, what is the potential energy and kinetic energy

11:58 of the ball, 8 meter to the ground.

12:00 And lastly, what is the speed of the ball,

12:03 just before striking the ground?

12:07 From the parameters provided, our mass is 1.8 kg.

12:15 Our G still remains the same, 10 meter per seconds.

12:21 And our height, H equals 200 meter.

12:28 Now, for firstly, we also calculate potential energy.

12:33 Applying the formula, potential energy equals mg-ish.

12:39 That is equal to 1.8 multiplied by 10,

12:46 then multiplied by 200.

12:51 We have 30,000, 600,000 joules.

12:56 Then, the next step, we also calculate

13:02 the potential energy when the height is 8 meter.

13:08 At 8 meter, potential energy equals mg-ish.

13:20 And that is equal to 1.8 multiplied by 10,

13:28 multiplied by 8, and that is 1,440 joules.

13:36 So that is the energy processed by the body, the potential energy,

13:42 when it is falling a distance of 8 meter.

13:48 And lastly, the total kinetic energy, as usual, total energy,

13:57 equals potential energy plus kinetic energy.

14:03 So we have 3600 equals 1,440 plus kinetic energy.

14:17 Therefore, our kinetic energy is equal to 3600 minus 1,440.

14:26 So, we are left with 2,460 joules.

14:34 And lastly, to calculate the speed with which the object

14:40 strikes the ground, we relate the formula for kinetic energy

14:49 to that of potential energy.

14:54 Substituting the values half multiplied by 1.8,

14:59 multiplied by V squared equals 1.8,

15:06 multiplied by 10, then multiplied by 200.

15:12 From here, 1.2, I mean 1, all about 2, multiplied by 1.8

15:21 by V squared will be equal to 1.8 multiplied by 2000.

15:30 Therefore, 1.8 multiplied by V squared equals 2, multiplied by 1.8,

15:40 multiplied by 2,000.

15:43 And our V squared will not be equal to 2 by 1.8 by 2000,

15:52 all over 1.8, and from what we have here, 7,200,

16:11 all over 1.8 will give us 4,000.

16:17 Our V will not be, if this is V squared, our V will not be equal to square root of 4,000.

16:31 So that our V finally will not be equal to 63.2 m/s.

16:41 That is how we relate the formula of potential energy and kinetic energy

16:47 to obtain the speed with which the object strikes the ground.

16:52 Law of conservation of energy.

16:56 This states that energy can never be created or destroyed,

17:03 but it can be transformed from one form to another.

17:08 In another form, it can also be defined as a total energy in the system,

17:13 remains constant.

17:15 This means that a system will always have the same amount of energy

17:19 before and after, or less, and energy is added outside the system.

17:26 Now, renewable energy.

17:29 When we talk about energy, we want to call renewable energy and non-renewable energy.

17:36 For renewable energy, there are always clean energy obtained from natural resources

17:43 and they are constantly replenished.

17:45 When we talk about renewable energy, those are the energy that cannot be exhausted.

17:49 They are in exhaustive.

17:51 For example, the solar energy.

17:54 In us most are their sound.

17:57 Their slides from the sound.

17:59 The solar energy will continue to be dear.

18:02 They will continue to get our solar energy.

18:05 By putting our apparatus in place, our instruments, the solar collector,

18:11 you can always get solar energy.

18:14 Unlike crude oil, where we keep on after exploration,

18:20 you explore, you explore at a particular time,

18:23 there will be no more oil in the particular oil block.

18:26 Those ones are exhaustive.

18:28 And those ones belong to the category of non-renewable energy.

18:32 So for renewable energy, those are energy that can be replaced often

18:37 and often they can be replenished.

18:39 And we have about seven types and this include one, wind energy.

18:44 We discovered that a free sense, wind is not being used to generate energy.

18:51 Just install the wind bill, allow wind to blow.

18:56 By the time the wind blew, it gives out energy.

19:00 And those energy are not being used for generation of electricity.

19:05 Also, we have hydroelectric energy.

19:09 Those are the energy obtained by falling of water through a barrier called dam.

19:15 This water by the time they fall, they drive with turbine.

19:18 And by the time they drive the turbine,

19:20 the turbine is connected to a generator or a dynamo,

19:23 which produce electricity.

19:25 Just like what we have in Shiroro dam, Kanji dam, I should juray dam.

19:30 Those ones are being used to produce electricity.

19:34 Likewise, ocean water are also being used

19:37 as a source of energy nowadays to generate electricity.

19:42 Then, apart from that, we have geothermal energy

19:45 that is, you harness the heat under the heat,

19:49 which are not being used or they are not being converted

19:52 to use for use in our home and at the same time to generate electricity.

19:58 Then, apart from that, we talk about biomass.

20:00 This is a conversion of solid fuel from plant material to generate electricity.

20:07 Likewise, hydrogen is also being used to produce electricity,

20:11 most especially in the interior of the sun.

20:15 We are hydroging atoms or isotopes are allowed to combine.

20:20 And by the time to combine through the process of nuclear fusion,

20:24 they also give out large amounts of heat,

20:26 which are also being converted to use as generation for generation of

20:30 electricity or power.

20:32 Likewise, solar energy, energy from the sun.

20:35 So, we also obtain our energy from the sun.

20:38 And at the same time, tie that energy from tie that wave's currents.

20:43 They also, they are also being used to drive turbines.

20:46 Then, non-renewable energy sources.

20:49 These are energies that are non-natural,

20:51 and they cannot be replaced by natural means.

20:54 That means, by natural means to cope with the consumption risk.

20:58 That is, they are consumable.

21:00 Examples are oil, natural gas, coal and nuclear energy.

21:05 Oil, coal and natural gas are called fossil fuel.

21:10 Fossil fuel, in the sense that they were formed within the Earth

21:13 from dead plants, anima, over millions of years ago.

21:18 Advantage is of renewable energy.

21:20 One, they don't run out, or they are not used up.

21:23 The more you keep on using them, the more they keep on replacing themselves.

21:27 Then, maintenance requirements are low,

21:30 harsh number of heads and environmental benefits.

21:34 And they reduce the lions on foreign energy sources.

21:37 They are clean, and they are shipped to run.

21:40 This advantage is of renewable energy.

21:43 It is difficult to generate large quantities of electricity

21:47 that are large as those produced by fossil fuel.

21:51 Sometimes, to set up those energy plants

21:56 are always very expensive.

21:58 Power.

22:00 Power is defined as the time rate of the work.

22:02 It is measured in joule or joule per second.

22:06 And the formula for power, just like what we have here,

22:10 power equals work done all over time.

22:16 And our work done, just like we discussed earlier,

22:23 is a function of force, multiplied by displacement all over time.

22:33 But from our knowledge of motion, we knew that velocity equals displacement.

22:39 Velocity equals displacement all over time.

22:54 So, that means our power can also be written as force multiplied by velocity.

23:04 And the unit still remains the same.

23:08 And the unit still remains the same.

23:12 And other unit of power is also horsepower.

23:16 We discussed that our pump machine, we will say it is one horsepower, 2.5 horsepower.

23:22 It's also a unit of power.

23:25 And one horsepower equals 745.7 watts.

23:33 So, other larger units of power are 1,000 watts, of course, 1 kilowatt.

23:40 And don't forget that it is this kilowatt that the Ph.N. people sell the energy we consume towards.

23:48 Likewise, 1,000 kilowatt, of course, 1 megawatts.

23:51 And 1,000 megawatt, of course, 1 gigawatt, gigawatt.

23:54 Example 1, a car drive the lower wood with the force of 18 newtons, F equals 18 newtons,

24:02 through a distance of 8 meter, distance 8 meter.

24:07 And our time is 4 seconds.

24:10 Calculate the power developed by the car.

24:15 From our formula, the power equals force times distance all over time.

24:21 So, that would be equal to 80, multiplied by 80 all over four.

24:27 So, we have 160 watts.

24:31 So, that means for that journey, the power developed by the car,

24:34 or is just about 160 watts.

24:41 Then, there's number 2. A tractor engine produces a force of 100,000 newtons.

24:46 When it is running at a speed of 72 kilometer power, what is the power developed by the tractor?

24:51 From our formula, we know that that is force multiplied by velocity.

25:01 The force is 100,000.

25:07 Much multiplied by our velocity, but velocity is given in terms of speed.

25:12 So, we need to convert our velocity to our speed to velocity.

25:17 And, in doing that, we have 20 meter per seconds.

25:21 Now, if we substitute 20 dA, that means we are going to have

25:28 2 million watts, and that is 17,000, 2,000 kilowatt.

25:38 Other examples, we have a rocket built up with a truss of 500,000 newtons.

25:46 After addition, the height of 250 kilometers in 29 seconds, what is the power developed by the rocket?

25:53 Putting our formula, the power, of course, worked all over time, substituted the value, force, 500,000

26:02 distance, will convert it from kilometer to meter, and that is 250,000 meter divided by the time,

26:08 which is in seconds. At the end of the day, we have 6,250 megawatts.

26:14 Likewise, the water pump will pump water upstairs,

26:19 to lift 800 grams of water to the height of 20 meter in 40 seconds, calculate the work done.

26:25 Our work done is 17 as MGH, that formula,

26:29 mass of water 800, multiplied by G, which is associated with gravity and time, which is just 20 seconds.

26:36 And, my height, which is 20 meter, you have 100,000 and 60,000 joules.

26:41 Now, the power developed, our power is worked all over time. That is 160,000 all over 40 seconds,

26:48 which is the type, and we have 4,000 watts. And lastly, just like what we did last,

26:56 we also have the same sequence, worked all over time, and at the end of the day,

27:01 we have 200,000 all over 30,000 which is 6,000, 666.7 watts.

27:07 Evaluation. At the end of the lesson, the student should be able to answer the following

27:15 questions. One, states the law of conservation of energy. Two, what is renewable and non-renewable energy?

27:22 Three, least five sources of renewable energy. Four, states four advantages and two disadvantages

27:29 of renewable energy sources. Five, what is non-renewable energy sources? Give three examples,

27:36 and lastly, define power, and states its units. Thank you for watching. My name is Stabelo,

27:42 Ehi. Till next time.