PhET/C3/Pendulum-Lab/English-timed

Time	Narration
00:01	Welcome to the Spoken Tutorial on Pendulum Lab simulation.
00:06	In this tutorial we will demonstrate, Pendulum Lab PhET simulation.
00:13	Here I am using: Ubuntu Linux OS version 16.04
00:20	Java version 1.8.0
00:25	Firefox web browser version 62.0.3
00:31	To follow this tutorial, Learner should be familiar with topics in high school physics.
00:38	Using this simulation, we will, Describe simple harmonic motion.
00:44	Demonstrate the oscillations of a pendulum.
00:48	Investigate the factors that affect the oscillations of a pendulum.
00:54	Explain Conservation of energy during motion of the pendulum.
01:00	Demonstrate the oscillations for a pair of pendulums.
01:05	Demonstrate the oscillations of a pendulum on other celestial bodies.
01:11	A simple pendulum has a fixed string attached to a bob.
01:17	Now we will define simple harmonic motion Simple harmonic motion arises when the force on the oscillating body is directly proportional to its displacement from its mean position. i.e., F α -x
01:38	In SHM there is a continuous interchange of kinetic and potential energies.
01:45	Here, mechanical energy is conserved.
01:49	Use the given link to download the simulation.
01:53	I have already downloaded the simulation to my Downloads folder.
01:58	Right click on pendulum-lab_en.html file.
02:02	Select the option Open with Firefox Web Browser.
02:07	Pendulum Lab simulation opens.
02:11	In the Pendulum lab simulation, we have three screens Intro Energy Lab
02:21	Click on Intro screen to open it.
02:25	In this screen we have, A blue coloured pendulum.
02:30	A Protractor to show the changes in the angle of the pendulum.
02:35	A ruler to measure the distance from the fixed point to the centre of mass.
02:41	Length and Mass sliders to change the length and mass of the pendulum.
02:47	Gravity and Friction sliders to change gravity and friction.
02:53	At the bottom left corner of the screen we have grey coloured box.
02:58	It has the following check boxes.
03:02	A Ruler A Stopwatch and A Period Trace.
03:09	At the bottom of the screen we have, A Pendulum and a Pair of pendulum buttons.
03:16	Stop button to stop the oscillations of the pendulum.
03:21	Play/Pause and Step buttons.
03:25	Normal or Slow radio buttons to change animation speed.
03:30	And a Reset button to reset the simulation.
03:35	For the pendulum, reference line on the bob is the centre of mass.
03:41	Pendulum’s angle can be changed from 180 to -180 degrees.
03:47	Drag the pendulum to a particular angle say 30 degrees and allow to oscillate.
03:55	Here, default length of pendulum is 0.70 m.
04:01	Now click and drag the Length slider towards left till 0.30 m.
04:08	Observe that as we decrease the length, pendulum oscillates faster.
04:14	Drag it back to 0.70 m.
04:19	The default mass of pendulum is 1 kg.
04:24	Click and drag the mass slider towards left till 0.50 kg.
04:32	Observe that as we change the mass, it does not affect the oscillations of the pendulum.
04:39	Note that Friction slider is at None.
04:43	Now click and drag the Friction slider towards Lots.
04:48	Observe that the oscillations of the pendulum slow down.
04:53	After sometime pendulum stops oscillating.
04:57	This is due to increase in friction, as friction damps the oscillations of the pendulum.
05:04	Click on Reset button to reset the simulation.
05:09	Now let us measure time for 10 oscillations at different lengths.
05:16	We will make a tabular column, to show length and time for 10 oscillations of a pendulum.
05:24	Next select the Stop watch to record the time for 10 oscillations.
05:31	We will count 10 oscillations for length 0.70 m.
05:37	Click and drag the pendulum at an angle of 30 degrees to count number of oscillations.
05:44	Now we will count the 10 oscillations.
05:47	one, two, three, four, five, six, seven, eight, nine, ten.
06:05	Note the value in the table.
06:09	To find the mean time taken for 10 oscillations, we need to measure the time for 0.70 m again.
06:19	Click on Reset button of the Stop watch to take the count of next 10 oscillations.
06:26	Click on Stop button to stop the oscillations.
06:31	Change the length to 0.60 m.
06:35	Follow the same steps to count 10 oscillations for length 0.60 m.
06:43	Here I have already taken the observations for two different lengths.
06:49	As an assignment, Change the length of the pendulum to 0.50 m, 0.40 m and 0.30 m.
07:01	Count for 10 oscillations.
07:05	Note down the time.
07:08	Next we will move on to Energy screen.
07:12	Click on Energy screen button at the bottom of the interface.
07:18	In this screen we will explain how energy is conserved during the oscillations of the pendulum.
07:25	Energy screen has almost same tools as that for Intro screen except for the Energy Graph.
07:34	Click and drag the pendulum to 60 degrees and allow it to oscillate.
07:40	Observe the graph.
07:42	From the drop down below Gravity select Jupiter.
07:47	Observe the change in graph.
07:50	Click on the Slow radio button to see the change in graph during the oscillations of the pendulum.
07:58	Here, we observe that at the extreme positions the potential energy is maximum.
08:05	At the mean position the kinetic energy is maximum.
08:10	Therefore, the total mechanical energy is conserved during the motion.
08:16	Click on the Normal radio button.
08:19	Now we will see the effect of friction in the graph.
08:23	Click and drag the Friction slider towards Lots.
08:28	Observe that due to increase in friction there is sudden increase in thermal energy.
08:35	After sometime total mechanical energy equals thermal energy.
08:41	This is because friction damps oscillations of the pendulum.
08:47	Now we will move to Lab screen.
08:50	In this screen we have the same tools that are included in previous screens.
08:57	Additionally we have velocity and Acceleration check boxes at the top left corner.
09:04	And Period Timer instead of Period Trace.
09:08	Select the pair of pendulums.
09:11	Here, we can see that on the top right corner, there are two lengths and two mass sliders.
09:19	The default length of second pendulum is 1 m.
09:24	Default mass is 0.50 kg.
09:29	Drag the blue pendulum to 60 degrees and allow it to oscillate.
09:35	Similarly, drag the red pendulum.
09:40	Note that green colour is for Velocity vector.
09:44	And yellow is for Acceleration.
09:47	Select Velocity check box.
09:50	Select the Slow radio button to observe the velocity vector carefully.
09:56	Here, we observe that velocity is maximum at its mean position.
10:01	It decreases at the extreme positions.
10:06	This is due to maximum kinetic energy at the mean position.
10:12	Similarly, let us select Acceleration vector and observe the change in acceleration.
10:20	As an assignment, Explain why acceleration is maximum at extreme positions?
10:29	Click on Reset button to reset the simulation.
10:34	Using the pendulum, we will compare calculated and measured Time period for different lengths.
10:42	Let us make a tabular column for Length L, Time period T (Calculated) and Time period T (Measured).
10:51	We can calculate the time period using formula T=2π√(l/g)
11:00	Where ‘l’ is length and ‘g’ is acceleration due to gravity.
11:06	Value of g = 9.81 m/s^2.
11:13	Select Period Timer.
11:16	On the right side of the screen a Period Timer appears.
11:21	Note down 0.70 m in the length column.
11:26	Here I have already calculated the time period using the formula.
11:32	We will measure the time period from the simulation.
11:38	Now click and drag the pendulum to 40 degrees.
11:43	Click on the start button of the Period Timer.
11:47	Value for time period appears on the screen.
11:51	Note the time period in the measured column.
11:55	Now change the length to 0.60 m.
12:00	Again click on the Period Timer.
12:06	Note the value in the table.
12:09	As an assignment, Change the lengths of the pendulum to 0.50 m, 0.40 m, and 0.30 m.
12:21	Note down the measured Time period.
12:24	Calculate the time period using the formula.
12:27	Compare the calculated and measured time period values.
12:34	Next Reset the simulation.
12:37	Drag the pendulum to 30 degrees to oscillate.
12:41	Note that acceleration due to gravity on Earth is 9.81 meter per second square.
12:49	Now select Jupiter from the drop down list.
12:53	Observe the change in oscillations of the pendulum.
12:58	Note that value of acceleration due to gravity on Jupiter is more than that on Earth.
13:07	As an assignment, Observe the oscillations on other celestial bodies.
13:14	Let us summarise
13:16	In this tutorial, we have demonstrated, How to use Pendulum lab PhET simulation.
13:24	Using this simulation, we have, Described simple harmonic motion.
13:30	Demonstrated oscillations of a pendulum.
13:34	Investigated the factors that affect the oscillations of a pendulum.
13:40	Demonstrated how energy is conserved during oscillations.
13:45	Demonstrated the oscillations of a pair of pendulums.
13:50	Observed the oscillations on other celestial bodies.
13:55	The video at the following link summarizes the Spoken Tutorial project.
14:01	Please download and watch it.
14:04	The Spoken Tutorial Project team, conducts workshops using spoken tutorials and gives certificates on passing online tests.
14:14	For more details, please write to us.
14:18	Please post your timed queries in this forum.
14:22	This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching.
14:30	Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.
14:37	More information on this mission is available at this link.
14:42	This is Himanshi Karwanje from IIT-Bombay.
14:46	Thank you for joining.

Contributors and Content Editors

Karwanjehimanshi95