PhET-Simulations-for-Physics/C2/Energy-Skate-Park/English-timed

Time	Narration
00:01	Welcome to this tutorial on Energy Skate Park simulation.
00:06	In this tutorial, We will demonstrate Energy Skate Park, PhET simulation.
00:14	Here I am using- Ubuntu Linux OS version 14.04
00:22	Java version 1.7.0
00:26	Firefox Web Browser version 53.02.2
00:32	To follow this tutorial, learner should be familiar with topics in high school physics.
00:40	Using this simulation, we will learn: 1. About law of conservation of energy.
00:48	2. To show pie chart and bar graphs for energy changes.
00:53	3. To use Energy vs Position graph, to show the energy value at a particular position.
01:00	4. To change location and observe the energy changes.
01:04	5. About change in energy due to change in mass and friction.
01:09	According to law of conservation of energy, energy can neither be created nor destroyed.
01:17	It can only be converted from one form to another.
01:22	The total energy before and after the transformation is conserved.
01:27	Potential energy is the energy possessed by an object by virtue of its position.
01:34	PE = mgh where m is mass of the object , g is acceleration due to gravity and h is height.
01:43	Kinetic energy is the energy possessed by a body due to its motion.
01:49	KE =1/2 mv2 where m is mass of object and v is velocity.
01:57	Let us start the demonstration.
02:00	Use the given link to download the simulation.
02:04	I have already downloaded Energy skate park simulation to my Downloads folder.
02:11	To run the simulation, open the terminal.
02:15	At the prompt, type: cd Downloads and press Enter.
02:23	Then type: java space hyphen jar space energy hyphen skate hyphen park underscore en dot jar and press Enter.
02:37	Energy Skate Park simulation opens.
02:41	This is the interface of Energy skate Park simulation.
02:46	Using this simulation, let's see how energy transformations happen in real world applications.
02:54	Screen has a menu bar with menu items- File,
03:00	Tracks,
03:02	Help.
03:04	Screen has a PhET skater oscillating in a default loop.
03:09	To change the track of the skater, click on Tracks menu.
03:14	Menu shows a list of tracks to choose.
03:19	On the right side, there is a panel with controls.
03:24	These controls are used to change the attributes in the simulation.
03:29	Click on Reset to reset the simulation. Click on Yes to confirm the reset.
03:37	Click on Choose Skater button on the panel.
03:41	Choose Skater panel opens.
03:44	This panel shows different skaters along with their mass.
03:49	By default, PhET Skater with 75 kg mass is selected.
03:55	Click on OK button.
03:58	At the bottom of the screen, we have Sim Speed slider to control the speed of the animation,
04:06	Play/Pause and Step buttons,
04:10	Zoom in and zoom out buttons.
04:13	By default, Sim Speed slider is on fast.
04:17	Drag the Sim speed slider between slow and fast.
04:22	To show the path, click on Show Path button in Path section.
04:27	Observe the purple dots on the track.
04:30	Click on Stop button and then pause the simulation.
04:36	Click on any purple dot on the track.
04:40	The following information will be displayed:
04:44	Kinetic energy,
04:46	Potential energy,
04:48	Total energy,
04:50	Height,
04:52	Speed of skater.
04:54	Click on Clear button to clear the path.
04:58	Now, click on Play button to play the simulation.
05:02	On the right side panel, under Energy Graphs section, click Show Pie Chart check-box.
05:09	Observe that with Thermal check-box also gets selected.
05:14	Pie chart shows conversion of kinetic energy to potential energy and vice-versa.
05:20	Energy indicator box is shown on the top right corner of the screen.
05:26	This box helps to identify the energy changes in the Pie Chart.
05:31	In this case, potential energy is gravitational potential energy.
05:36	It is due to change in height of the skater in the gravitational field.
05:41	As the skater moves downwards, his potential energy decreases and kinetic energy increases.
05:49	As skater moves upwards his potential energy increases and kinetic energy decreases.
05:56	Drag the sim speed slider towards Slow.
06:00	You can still see a small amount of potential energy at the bottom of the track.
06:06	This is because track is at a height above the ground level.
06:11	Drag the track to the ground level.
06:15	Observe that skater has zero potential energy at the bottom of the track and zero kinetic energy at the top.
06:23	Now I will drag the track above the ground level.
06:27	Click on Potential Energy Reference check-box.
06:31	P.E=0 at this dotted line will display at the bottom of the screen.
06:37	Drag Potential Energy Reference line upwards to touch the bottom of the track.
06:43	Observe that now skater has zero potential energy at the bottom of the track.
06:49	Next, click on Bar Graph button.
06:52	A bar graph with four energies is shown.
06:56	Note the energy changes as the skater moves back and forth on the track.
07:02	Here total energy of the skater remains constant.
07:06	Therefore it obeys the law of conservation of energy.
07:10	Let us change the shape and height of the track.
07:14	Click on any blue point and drag.
07:17	Note the increase in Total energy with an increase in height of the track.
07:22	Close the Bar Graph.
07:24	Click on Reset button to reset the simulation.
07:29	Next click on Energy vs. Position button.
07:33	Energy vs Position graph will display.
07:37	Drag the track to the left side to view the graph and skater simultaneously.
07:43	Notice the energy changes with respect to position of skater.
07:48	Here you can see a moving dotted line.
07:52	It represents energy of the skater at a particular position on the track.
07:58	Graph has four energy check-boxes at the bottom.
08:02	To view the graph of any specific energy, un-check remaining check boxes.
08:09	Click on Pause button to pause the simulation.
08:13	Click on Copy button.
08:16	Copy button helps to show the energy values at particular position on the graph.
08:22	Close the graphs.
08:25	Now click on Energy vs. Time button.
08:29	Energy vs. Time graph opens.
08:33	At the bottom of the graph, we have- Sim Speed slider,
08:38	Stop/Go, Playback,
08:42	Step, Rewind and Clear buttons.
08:49	Click on Play button to play the simulation.
08:56	Click on Stop button.
08:59	Lets drag the sim speed slider between slow and fast.
09:04	Then click on Playback button.
09:07	Notice a violet vertical line moving across the path.
09:12	Note the kinetic, Potential and Total energy values at a given time.
09:20	Note that Total energy remains constant.
09:24	But, kinetic energy changes to potential energy and vice-versa.
09:29	Here Thermal energy is zero as there is no friction.
09:33	Close the Energy vs. Time graph.
09:36	Click on Reset button to reset the simulation.
09:40	Let us see how mass of the skater will affect the total energy.
09:45	Scroll to the bottom of the panel.
09:48	Click on Edit skater button.
09:51	Scroll down to see Mass text-box and Mass Slider.
09:57	By default, Mass is 75 kg.
10:01	Click on Energy Vs. Time button to open the graph.
10:06	Drag the Mass slider gradually towards 200.
10:10	Observe the change in energy as we change the skater's mass in the graph.
10:16	Close the Energy Vs. Time graph.
10:19	Now we will take the skater to different planets.
10:24	Scroll up the panel.
10:27	Click on Reset button to reset the simulation.
10:31	In the Location section, by default, Earth is selected.
10:35	Click on Energy vs. Time button.
10:39	Under Location section, click on Moon radio-button.
10:44	Observe that Skater flies off because moon has low Gravity value.
10:50	Click on Return Skater button.
10:53	Here Gravity value is 1.62 N/kg which is less than that of Earth.
11:00	This results in decrease in the speed of skater.
11:04	Here, Total energy decreases as gravity on Moon is less than that of Earth.
11:10	Similarly, explore Jupiter and Space locations and compare the energy changes.
11:17	Close the Energy vs. Time graph.
11:21	Let us study the energy distribution for tracks with and without friction.
11:26	Click on Reset button to reset the simulation.
11:30	Scroll down to panel and click on Track Friction button.
11:35	Scroll down to see Coefficient of Friction slider.
11:40	Click on Energy vs.Time button.
11:44	Drag the Coefficient of Friction slider gradually from None to Lots.
11:50	Observe the energy changes.
11:53	Here, part of energy is converted to Thermal energy due to friction.
11:59	This is due to the resistance in motion caused by friction.
12:04	Friction opposes the motion of the skater.
12:08	It causes him to lose energy and slow down.
12:12	Close the Energy vs. Time graph.
12:15	As an assignment: Select Double Well track from Tracks menu and observe the energy changes.
12:24	Compare the energy changes in Double well track with Double Well Roller Coaster Mode.
12:30	Find the changes in the thermal energy
12:34	and give an explanation. (Hint-Right click on the Track and select Roller Coaster Mode).
12:43	Using Tracks box, create tracks and observe the change in energies.
12:49	Let us summarise.
12:52	In this tutorial, we have demonstrated, How to use Energy Skate Park, PhET simulation.
13:01	Using this simulation we have learnt, 1. About law of conservation of energy.
13:08	2. To show pie chart and bar graphs for energy changes.
13:13	3. To use Energy vs Position graph to show the energy value at a particular position.
13:20	4. To change location and observe the energy changes.
13:24	5. About change in energy due to change in mass and friction.
13:29	The video at the following link summarizes the Spoken Tutorial project. Please download and watch it.
13:38	The Spoken Tutorial Project team conducts workshops using spoken tutorials and gives certificates on passing online tests.
13:47	For more details, please write to us.
13:51	Please post your timed queries on this forum.
13:55	This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching.
14:03	Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.
14:11	More information on this mission is available at this link.
14:16	This is Meenal Ghoderao from IIT-Bombay. Thank you for joining.

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