PhET/C3/Pendulum-Lab/English-timed
From Script | Spoken-Tutorial
| 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. |
| 01:21 | Simple harmonic motion arises when the force on the oscillating body is directly proportional to its displacement from its mean position. |
| 01:33 | That is 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. |
