Apps-On-Physics/C2/Keplers-laws/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:01 | Welcome to the Spoken Tutorial on Kepler's Law. |
| 00:05 | In this tutorial we will,
Verify Kepler's first law using Kepler's first law simulation. |
| 00:14 | Calculate Aphelion and Perihelion distances. |
| 00:18 | Verify Kepler's second law using Kepler's second law simulation. |
| 00:24 | Here I am using,
Ubuntu Linux OS version 16.04 |
| 00:31 | Firefox web browser version 62.0.3 |
| 00:36 | To follow this tutorial, learner should be familiar with Apps on Physics. |
| 00:43 | For pre-requisitie tutorials please visit this site. |
| 00:48 | Use the given link to download the Apps. |
| 00:52 | I have already downloaded Apps on Physics to my Downloads folder. |
| 00:57 | In this tutorial we will use, Kepler's First Law and Kepler's Second Law Apps. |
| 01:06 | Double click on html5phen folder, then double click on phen folder. |
| 01:14 | Right-click on keplerlaw1_en.htm file. |
| 01:20 | Select the option Open With Firefox web Browser. |
| 01:25 | Kepler's First Law App opens in the browser. |
| 01:29 | This is the interface of Kepler's First Law App |
| 01:33 | Here is the Kepler's First Law of undisturbed planetary motion. |
| 01:39 | It states that, The orbit of each planet is an ellipse and the Sun is at one focus. |
| 01:47 | Let us scroll down the screen. |
| 01:51 | The green control panel shows the parameters that we can change. |
| 01:56 | From the drop down list select any planet or Halley's Comet.
By default Mercury is selected. |
| 02:06 | Here we can change the Semimajor axis from 0.1 to 100 AU. |
| 02:12 | These lengths are in astronomical units.
1AU = 1.495 X 10^11 m |
| 02:23 | This is the average distance between the Earth and the Sun. |
| 02:28 | The Numerical eccentricity should be less than 1. |
| 02:32 | The App automatically calculates the Semiminor axis and Distance from the Sun. |
| 02:38 | Since the planet is revolving around the Sun, its current distance changes continuously. |
| 02:44 | Mercury's Minimum and Maximum Distance from the Sun is measured. |
| 02:50 | Minimum measured value is 0.307 AU.
And Maximum measured value is 0.467 AU. |
| 03:00 | At the bottom of the green panel there are three check-boxes. |
| 03:05 | Elliptical orbit', ‘Axes and Connecting lines. |
| 03:11 | Click on Elliptical orbit check-box. |
| 03:15 | Observe that the orbit now has two positions, namely Aphelion and Perihelion. |
| 03:23 | Click on Pause button to pause the simulation. |
| 03:27 | Aphelion is the Maximum distance and Perihelion is the Minimum distance from the Sun. |
| 03:34 | Select Connecting lines check-box. |
| 03:37 | Here we can see the foci F and F prime of the elliptical orbit. |
| 03:43 | Note that the connecting lines between the planet and the foci are drawn. |
| 03:48 | Click on Resume button. |
| 03:51 | Select the Axes check-box. |
| 03:54 | Here we can see that semi-major axis and semi-minor axis are drawn. |
| 04:00 | Let us calculate the Aphelion and Perihelion distances of Mercury using the formula. |
| 04:08 | Formula to calculate Aphelion and Perihelion distances: |
| 04:!3 | Ra=a(1+e)
Rp=a(1-e) |
| 04:23 | Where, Ra is Aphelion distance. |
| 04:27 | Rp is Perihelion distance. |
| 04:30 | a is semi-major axis.
e is eccentricity. |
| 04:36 | Let us make a tabular column to show Planets, Eccentricity, Aphelion and Perihelion distances. |
| 04:46 | Let us calculate the Maximum and Minimum distance of Mercury from the Sun. |
| 04:52 | Substitute the values of Semi-major axis and eccentricity in the formula from the App. |
| 04:59 | These are the calculated values of the Aphelion and Perihelion distances. |
| 05:05 | Now we will compare these values with the ones shown in the App. |
| 05:10 | Observe that the values are comparable. |
| 05:14 | From the drop down I will select Venus. |
| 05:18 | Observe that the values have changed for Venus. |
| 05:22 | Similarly I have calculated the Maximum and Minimum distance for Venus.
And entered these values in the table. |
| 05:31 | As an assignment
Calculate the Aphelion and Perhelion distances of the other planets. |
| 05:38 | Use the values of semi-major axis and eccentricity shown in the App. |
| 05:44 | Complete the table and verify the values with the ones shown in the App. |
| 05:49 | From the drop down list select Halley’s comet. |
| 05:53 | Observe that the orbit of Halley’s comet is different from the other planets. |
| 05:58 | It's orbit around the Sun is highly elliptical. |
| 06:02 | This is because the numerical eccentricity of the Halley’s comet is close to 1. |
| 06:09 | Therefore there is a large difference in the values of semi-major and semi-minor axis. |
| 06:15 | Let us know more about Halley’s comet. |
| 06:18 | Halley’s comet is a periodic comet. |
| 06:20 | It returns to Earth’s vicinity in about every 75 years. |
| 06:26 | A comet appears as a bright head with a long tail. |
| 06:31 | The tail of a comet is always directed away from the Sun. |
| 06:36 | Now we will move on to the next App. |
| 06:39 | To open the App right click on keplerlaw2_en.htm file and Open With Firefox Web Browser. |
| 06:50 | The App opens with Kepler's Second Law of the undisturbed planetary motion. |
| 06:56 | The law states that,
The line joining the planet to the Sun sweeps out equal areas in equal intervals of time. |
| 07:06 | Scroll down to see the interface. |
| 07:09 | In the green control panel, App measures the Distance from the Sun and Velocity. |
| 07:15 | The current velocity of the planet is changing continuously as the planet is revolving. |
| 07:22 | The Minimum and Maximum velocity of the planet is measured here. |
| 07:27 | At the bottom there are two check-boxes, Sectors and Vector of velocity. |
| 07:35 | By default Sectors is selected. |
| 07:39 | Next to the Sectors check-box, a slider is provided to change the area of the sector. |
| 07:46 | Select Vector of velocity. |
| 07:50 | Here the black velocity vector shows the direction of velocity of the planet. |
| 07:56 | The maximum velocity with which Mercury revolves is 59.1 km/s. |
| 08:04 | Mercury is the closest planet to the Sun so it moves with a greater velocity. |
| 08:11 | Now I will show the velocity for Jupiter. |
| 08:14 | Select Jupiter from the drop down list. |
| 08:18 | Jupiter has less velocity than that of Mercury. |
| 08:23 | Planets far away from the Sun have less velocity as compared to the planets that are near. |
| 08:30 | This is because the Sun’s gravitational pull is stronger on the planets that are close to it. |
| 08:37 | Observe the pink and green digital clocks. |
| 08:41 | They record the time when the planet sweeps the sectors. |
| 08:45 | This time is expressed in orbital period. |
| 08:49 | Let’s drag the sector slider to maximum. |
| 08:53 | Notice that as we increase the area, time increases. |
| 08:59 | The Orbital period is the time taken by the celestial object to go around the orbit of another celestial object. |
| 09:08 | Select the Saturn from the drop down list. |
| 09:12 | Observe that the sweep time for each sector in Saturn is same. |
| 09:18 | As an assignment
Select planets Venus and Uranus from the drop down list. |
| 09:25 | Observe the difference in the velocity.
Explain your observation. |
| 09:31 | Let us summarise |
| 09:33 | Using these Apps we have,
Verified Kepler's first law using Kepler's first law simulation. |
| 09:41 | Calculated Aphelion and Perihelion distances. |
| 09:45 | Verified Kepler's second law using Kepler's second law simulation. |
| 09:51 | These Apps were created by Walter Fendt and his team. |
| 09:55 | The video at the following link summarizes the Spoken Tutorial project.
Please download and watch it. |
| 10:03 | The Spoken Tutorial Project team conducts workshops and gives certificates.
For more details, please write to us. |
| 10:12 | Please post your timed queries on this forum. |
| 10:16 | Spoken Tutorial Project is funded by MHRD, Government of India. |
| 10:22 | This is Himanshi Karwanje from IIT-Bombay.
Thank you for joining. |
