Apps-On-Physics/C2/Keplers-laws/English-timed

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.

Contributors and Content Editors

PoojaMoolya