Difference between revisions of "PhET/C3/Gravity-and-Solar-system/English-timed"

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|| Using these simulations we will -  Describe the relation between Sun, Earth, Moon and satellite.  
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where '''G''' is universal gravitation constant  
 
where '''G''' is universal gravitation constant  
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|| The '''Spoken Tutorial Project''' team: conducts workshops using spoken tutorials and  
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|| The Spoken Tutorial Project team: conducts workshops using spoken tutorials and  
  
 
gives certificates on passing online tests.  
 
gives certificates on passing online tests.  

Revision as of 17:46, 8 August 2018

Time Narration
00:01 Welcome to this tutorial on Gravity and Solar System.
00:06 In this tutorial we will, Demonstrate Gravity and Orbits and My Solar System, PhET simulations.
00:16 Here I am using- Ubuntu Linux OS version 14.04
00:23 Java version 1.7.0 and
00:27 Firefox Web Browser version 53.02.2
00:34 To follow this tutorial, learner should be familiar with topics in high school science.
00:42 Using these simulations we will -

1. Describe the relation between Sun, Earth, Moon and satellite.

00:51 2. Study the effect of mass and distance on gravitational force.
00:56 3. Explain how gravity controls the motion of our solar system.
01:02 4. Identify the variables that affect the strength of gravity.
01:08 5. And determine the gravitational force.
01:12 In our solar system, all the celestial objects revolve around the Sun.
01:18 These objects are planets, moons, comets, asteroids, meteors and meteorites.
01:27 There exists a force of attraction between the Sun and the celestial objects.
01:34 This force of attraction is gravitational force.
01:39 Let us begin the demonstration.
01:43 Use the given link to download the simulation.
01:48 I have already downloaded Gravity and Orbits simulation to my Downloads folder.
01:55 To open the simulation, right click on gravity-and-orbits_en.html file.
02:01 Select Open With Firefox Web Browser Option.
02:06 Simulation opens in the browser.
02:10 This is the interface of Gravity and Orbits simulation.
02:16 The interface has two screens.

Model

To Scale.

02:22 Let us begin our demonstration with Model screen.
02:26 Click on Model screen to open it.
02:29 On the right side of the screen you can see a box.
02:34 It has four solar system like models.
02:38 Next to models there is a gray coloured, Reset button.
02:43 This button sets the solar system to its default state.
02:48 We can select Gravity, using on and off radio buttons.
02:54 Below Gravity, we have check-boxes for-

Gravity Force

Velocity

Path and

Grid .

03:03 Click on all the check-boxes.
03:06 Below this box we have another box.

It consists of sliders to change the mass of Star and Planet.

03:15 Bottom of the screen we have, Fast Forward, Normal and Slow motion radio buttons to change the animation speed.
03:25 By default Normal speed is selected.
03:29 Also there are Rewind, Play/Pause and Step buttons.
03:35 Clear button to reset the Earth Days count.
03:39 Reset button to reset the simulation.
03:43 By default Sun and Earth system is selected.
03:48 Now click on Play button.
03:51 Notice that, Earth revolves around the sun along a circular path.
03:57 This circular motion is due to centripetal force.
04:02 Centripetal force, causes change in acceleration and keeps the body moving along the circular path.
04:11 This force acts towards the center.
04:15 This circular path is its orbit.
04:19 Earth changes its direction of revolution at every point on the orbit.
04:25 Notice that, direction of Earth's velocity is perpendicular to Sun's gravitational pull.
04:32 Now Let us count Earth Days.
04:35 Click on Reset arrow to bring the sun and earth to its default position.
04:42 Observe the changes in the Earth Days as earth orbits the sun.
04:48 Now we will change the animation to slow to count the days precisely.
05:00 Click on Pause to pause the simulation.
05:04 Earth takes 365 days to complete one revolution.
05:09 Next we will see what happens to earth in the absence of gravity.
05:14 Click on off radio button.
05:17 Now we will change the animation to normal.
05:21 Then click on Play button.
05:24 Observe that, In the absence of Gravity, Earth files off along a straight line.
05:31 This motion is tangential to the circular path.
05:35 Click on Return Objects button.
05:38 Earth will return to its default position.
05:42 Now we will see the effect of change in mass on an orbit.
05:48 By default the Star Mass slider is at Our Sun.
05:53 Let's drag the Star Mass slider towards 1.5.
05:58 As you drag, observe the increase in size of the star.
06:03 Next, click Gravity's on radio button and then Play button.
06:10 Observe the path of the orbit.
06:13 Earth now moves in an elliptical path.
06:17 Size of the orbit also becomes small.
06:21 Here sun is not at the centre of the orbit.
06:26 Note that, Earth Days decrease with the increase in the mass of the sun.
06:32 Drag the Planet Mass slider towards 1.5.
06:37 Notice that force of gravity between them increases.
06:42 Click on Pause button to pause the simulation.
06:46 Click on the planet and drag it away from the sun.
06:51 Click on the Play button.
06:53 Observe that, gravitational force decreases with increase in the distance between planet and sun.
07:01 Click on Pause button. Click on Reset button to reset the system.
07:08 Now select Sun, Earth and Moon system.
07:12 Drag the slider towards + sign to zoom in the view.
07:17 Then click on Play button.
07:20 Notice that, moon is in spiral orbit with earth while earth is in circular orbit with sun.
07:29 Here moon is a satellite of the earth.
07:34 As an assignment, Using Model screen, Explore earth, moon and earth, satellite systems.
07:43 Now we will move on to To Scale screen.
07:47 Click on To Scale screen at the bottom of the interface.
07:52 To Scale screen has same tools as that of Model screen.
07:57 This screen has two additional check-boxes-

Mass and

Measuring Tape

08:04 Click on Mass, Path and Grid check-boxes.
08:09 By default sun and earth system is selected.
08:14 Here, star's mass is 333 thousand Earth masses and planet's mass is 1 Earth mass.
08:24 Click on Play button to show the path of revolution.
08:28 Then click on pause button.
08:31 Lets measure the distance between star and Earth.
08:35 Check against Measuring Tape check-box.
08:39 Uncheck Mass check-box.
08:42 This will enable us to measure the distance precisely.
08:47 Drag the zoom in slider towards + sign to zoom in the view.
08:52 Place the Measuring Tape on star and drag the other end to the planet.
09:00 Note the Distance between star and planet.
09:04 It is 91503 thousand miles.
09:10 This value may vary a little in your case because sun is also in motion.
09:17 Let us calculate gravitational force between Earth and sun.
09:22 Universal law of gravitation- Force of attraction between any two objects is proportional to the product of their masses.
09:33 It is inversely proportional to the square of the distance between them.
09:38 This force is along the line joining the centers of two objects.
09:44 Gravitational force is calculated by using following formula

where G is universal gravitation constant

09:53 capital M is mass of sun
09:58 small m is mass of earth
10:02 and d is distance between earth and planet
10:07 We substitute the values of G, capital M, small m and d in this formula.
10:15 This will give us the value of the Gravitational force between sun and Earth.
10:21 The value is 3.6 x1022 N(newton).
10:28 As an assignment, Using To Scale screen, Determine the gravitational force between Earth and satellite.
10:37 Now we will move on to My Solar System PhET simulation.
10:43 I have already downloaded My Solar System simulation to my Downloads folder.
10:50 To run the simulation, open the terminal.

At the prompt type cd Downloads and press Enter.

11:01 Then type, java space hyphen jar space my-solar-system_en.jar and press Enter.
11:17 My Solar System simulation opens.
11:21 This is the interface of My Solar System simulation.
11:26 Screen has a system drop-down box on the right side.
11:30 Here we can select a pair of solar systems of our choice.
11:36 Below the drop-down box there is another box.
11:40 It consists of Start, Stop and Reset buttons.
11:45 We have check-boxes for System Centered, Show Traces, Show Grid and Tape Measure.
11:55 Use these check-boxes as an when required.
11:59 There is a slider to control the speed of animation.
12:03 Screen is provided with Initial Settings at the bottom.
12:08 Here we can input the mass, position and velocity values in their respective boxes.
12:16 We can also use radio-buttons to select a number of bodies.
12:20 Now click on drop down arrow.
12:24 Scroll to Sun, planet, comet and click on it.
12:28 We see 3 coloured objects planet, sun and comet.
12:37 Red coloured arrow indicates the velocity.
12:41 It is a vector quantity indicated by V in circle.
12:46 Click on Start button and observe the orbits. Comet moves around the sun in an elliptical orbit.
12:55 Click on Stop button.
12:57 Hover the mouse over Sun, Planet and comet to get their mass, current position and velocity.
13:09 Click on start button.
13:12 After a few revolutions the comet collides with the Sun and disappears.
13:19 Select Four star ballet and click on Start button.
13:25 Observe the orbits. Then click on Stop button.
13:31 Hover the mouse on the bodies to get their mass, position and velocity.
13:39 As an assignment, Select various systems and observe the orbits.
13:46 Change the Initial settings and observe the changes in the orbits and Explain the observation.
13:54 Let us Summarise.
13:57 In this tutorial we have demonstrated, How to use Gravity and Orbits and My Solar System, PhET simulations.
14:07 Using this simulations we have, Described the relation between Sun, Earth, Moon and Satellite.
04:15 Studied the effect of mass and distance on gravitational force.
14:20 Explained how gravity controls the motion of our solar system.
14:25 Identified the variables that affect the strength of gravity.
14:30 And Determined the gravitational force.
14:35 The video at the following link summarizes the Spoken Tutorial project.

Please download and watch it.

14:44 The Spoken Tutorial Project team: conducts workshops using spoken tutorials and

gives certificates on passing online tests.

14:54 For more details, please write to us.
14:58 Please post your timed queries on this forum.
15:03 This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching.
15:12 Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.

More information on this mission is available at this link.

15:25 This is Meenal Ghoderao from IIT Bombay.

Thank you for joining.

Contributors and Content Editors

Madhurig, PoojaMoolya, Sandhya.np14

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