View source for PhET/C3/Pendulum-Lab/English


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|| '''Visual Cue'''
|| ''' Narration'''
|- 
|| '''Slide Number 1''' 

'''Title slide''' 
|| Welcome to the Spoken Tutorial on '''Pendulum Lab simulation.''' 

|- 
|| '''Slide number 2''' 

'''Learning objectives''' 
|| In this tutorial we will demonstrate, 

'''Pendulum Lab PhET simulation.''' 
|- 
|| '''Slide Number 3''' 

'''System Requirements''' 
|| Here I am using, 

Ubuntu Linux OS version 16.04 

Java version 1.8.0 

Firefox web browser version 62.0.3 

|- 
|| '''Slide Number 4''' 

'''Pre-requisites''' 
|| To follow this tutorial, 

Learner should be familiar with topics in high school physics. 

|- 
|| '''Slide Number 5 + 6''' 

'''Learning goals''' 
|| Using this '''simulation''', we will, 

* Describe simple harmonic motion 
*  Demonstrate the oscillations of a pendulum 
* Investigate the factors that affect the oscillations of a pendulum 
* Explain Conservation of energy during motion of the pendulum 
* Demonstrate the oscillations for a pair of pendulums 
* Demonstrate the oscillations of a pendulum on other celestial bodies 

|- 
|| '''Slide Number 7''' 
 
'''Simple Pendulum''' 
|| '''Simple Pendulum'''. 

A simple pendulum has a fixed string attached to a bob. 

|- 
|| '''Slide Number 8''' 

'''Simple harmonic motion.''' 



|| 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''' 


In '''SHM '''there is a continuous interchange of kinetic and potential energies. 

Here, mechanical energy is conserved. 

|- 
|| '''Slide Number 9''' 

'''Link for PhET Simulation'''. 


'''http://phet.colorado.edu''' 
|| Use the given link to download the''' simulation.''' 

'''http://phet.colorado.edu''' 
|- 
|| Point to the files in the downloads folder. 
|| I have already downloaded the '''simulation''' to my '''Downloads''' folder. 

|- 
|| Right click on '''pendulum-lab_en.html''' file. 

Select open with Firefox web Browser option. 
|| Right click on '''pendulum-lab_en.html''' file. 

Select the option '''Open with Firefox Web Browser.''' 

'''Pendulum Lab simulation''' opens. 

|- 
|| Point to each screen. 
|| In the pendulum lab simulation, we have three screens 

'''Intro''' 

'''Energy ''' 

'''Lab''' 

|- 
|| Click on the '''Intro screen'''. 
|| Click on '''Intro''' screen to open it. 

|- 
|| Point to Pendulum. 

Point to protractor. 

Point to the ruler. 
|| In this screen we have, 

A blue coloured pendulum 

A Protractor to show the changes in the angle of the pendulum. 

A ruler to measure the distance from the fixed point to the centre of mass. 

|- 
|| Point to''' Length''' and '''Mass sliders.''' 
|| '''Length '''and '''Mass''' sliders to change the length and mass of the pendulum. 

|- 
|| Point to '''Gravity '''and '''Friction''' sliders. 
|| '''Gravity''' and '''Friction''' sliders to change gravity and friction. 

|- 
|| Move the cursor on check box. 
|| At the bottom left corner of the screen we have grey coloured box. 

It has the following check boxes. 

A''' Ruler ''' 

A''' Stopwatch '''and 

A''' Period Trace'''. 

|- 
|| Move the cursor to the bottom of the screen. 
|| At the bottom of the screen we have, 

A''' '''pendulum and a pair of pendulum buttons. 

|- 
|| Point to '''Stop, Play/Pause and Step '''buttons. 
|| '''Stop''' button to stop the oscillations of the pendulum. 

'''Play/Pause''' and '''Step''' buttons. 

|- 
|| Point to '''Normal''' or '''Slow''' radio buttons. 
|| '''Normal''' or '''Slow''' radio buttons to change animation speed. 

|- 
|| Point to '''Reset''' button. 
|| And a '''Reset''' button to reset the '''simulation'''. 

|- 
|| Open the '''simulation''' 

Move the cursor on the '''bob'''. 
|| For the pendulum, reference line on the bob is the centre of mass. 

|- 
|| Click and drag the pendulum from '''180 to -180 degrees.''' 
|| Pendulum’s angle can be changed from '''180''' to '''-180''' degrees. 

|- 
|| Click and drag the pendulum to '''30 degrees.''' 
|| Drag the pendulum to a particular angle say '''30''' '''degrees''' and allow to oscillate. 

|- 
|| Move the cursor on the '''Length slider'''. 
|| Here, default length of pendulum is '''0.70 m'''. 

|- 
|| Click and drag the '''Length '''slider towards left. 
|| Now click and drag the '''Length''' slider towards left till '''0.30 m.''' 

|- 
|| Click and drag the '''Length slider '''towards 

Right. 
|| Observe that as we decrease the length, pendulum oscillates faster. 

Drag it back to '''0.70 m.''' 

|- 
|| Move the cursor on the '''Mass '''slider. 
|| The default mass of pendulum is '''1 kg.''' 

|- 
|| Click and drag the mass slider towards left till '''0.50kg '''in steps of 10. 
|| Click and drag the mass slider towards left till '''0.50 kg.''' 

Observe that as we change the mass, it does not affect the oscillations of the pendulum. 

|- 
|| Point to the '''Friction''' slider. 
|| Note that '''Friction''' slider is at '''None'''. 

|- 
|| click and drag the '''Friction '''slider towards '''Lots'''. 
|| Now click and drag the '''Friction''' slider towards '''Lots'''. 

Observe that the oscillations of the pendulum slow down. 

|- 
|| Point to the Pendulum. 
|| After sometime pendulum stops oscillating. 

This is due to increase in friction, as friction damps the oscillations of the pendulum. 
|- 
|| Click on the '''Reset''' button. 
|| Click on '''Reset''' button to reset the '''simulation'''. 

|- 
|| 
|| Now let us measure time for 10 oscillations at different lengths. 

|- 
|| '''Slide Number 10''' 

'''Tabular column''' 
|| We will make a tabular column, to show length and time for 10 oscillations of a pendulum. 

|- 
|| Click on the '''Stop watch''' check box. 
|| Next select the '''Stop watch''' to record the time for 10 oscillations. 

We will count 10 oscillations for length '''0.70 m'''. 

|- 
|| Click and drag the pendulum. 
|| Click and drag the pendulum at an angle of '''30 degrees''' to count number of oscillations. 

|- 
|| Click on '''Stopwatch.''' 
|| Now we will count the 10 oscillations. 

|- 
|| Point to table. 
|| Note the value in the table. 

|- 
|| '''Slide Number 11''' 

'''Tabular column''' 
|| To find the mean time taken for 10 oscillations, we need to measure the time for '''0.70 m''' again. 

|- 
|| Click on the '''Reset '''button of '''stop watch.''' 
|| Click on '''Reset '''button of the '''Stop watch''' to take the count of next 10 oscillations. 

|- 
|| Click on S'''top '''button. 
|| Click on '''Stop '''button to stop the oscillations. 

|- 
|| Click and drag the''' Length '''slider to''' 0.60 m.''' 
|| Change the length to '''0.60 m'''. 

|- 
|| Point to '''0.60 m.''' 
|| Follow the same steps to count 10 oscillations for length '''0.60 m'''. 

|- 
|| '''Slide Number 12''' 

'''Tabular column ''' 

|| Here I have already taken the observations for two different lengths. 

|- 
|| '''Slide Number 13''' 

'''Assignment''' 
|| As an assignment, 

Change the length of the pendulum to '''0.50 m, 0.40 m, '''and''' 0.30 m'''. 

Count for 10 oscillations. 

Note down the time. 

|- 
|| Move cursor on '''Energy '''Screen. 
|| Next we will move on to '''Energy '''Screen, 

Click on '''Energy '''screen''' '''button at the bottom of the interface. 

|- 
|| Click on the '''Energy '''Screen. 
|| In this screen we will explain how energy is conserved during the oscillations of the pendulum. 
 
|- 
|| Move the cursor on the '''Energy Graph'''. 
|| '''Energy '''screen has almost same tools as that for I'''ntro '''screen except for the '''Energy Graph'''. 

|- 
|| Move the cursor on the pendulum. 
|| Click and drag the pendulum to '''60 degrees''' and allow it to oscillate. 

Observe the graph. 

|- 
|| From drop down select '''Jupiter.''' 


Point to the graph. 
|| From the drop down below '''Gravity''' select '''Jupiter'''. 

Observe the change in graph. 
|- 
|| Click on the '''Slow '''radio button. 
|| Click on the S'''low '''radio button to see the change in graph during the oscillations of the pendulum. 

|- 
|| Move the cursor on graph. 
|| Here, we observe that at the extreme positions the potential energy is maximum. 

At the mean position the kinetic energy is maximum. 

Therefore, the total mechanical energy is conserved during the motion. 

|- 
|| Click on the '''Normal''' radio button. 
|| Click on the '''Normal''' radio button. 

|- 
|| Point to '''Friction'''. 
|| Now we will see the effect of friction in the graph. 

|- 
|| Click and drag the '''Friction '''slider towards '''Lots'''. 
|| Click and drag the '''Friction''' slider towards '''Lots'''. 

|- 
|| Point to''' Energy Graph.''' 
|| Observe that due to increase in friction there is sudden increase in thermal energy. 

|- 
|| Point to the '''Energy Graph'''. 
|| After sometime total mechanical energy equals thermal energy. 

 
This is because friction damps oscillations of the pendulum. 

|- 
|| Point to '''Lab '''screen. 
|| Now we will move to '''Lab '''screen. 

|- 
|| Click on the '''Lab''' screen. 


Point to the check boxes. 
|| In this screen we have the same tools that are included in previous screens. 

Additionally we have '''velocity '''and''' Acceleration''' check boxes at the top left corner. 

|- 
|| Point to''' Period timer.''' 
|| And P'''eriod Timer''' instead of P'''eriod Trace'''. 

|- 
|| From bottom of the screen click on pair of pendulums. 
|| Select the pair of pendulums. 

|- 
|| Move the cursor on the top right corner of the screen. 
|| Here, we can see that on the top right corner, 

there are two lengths and two mass sliders. 
|- 
|| Move the cursor on '''Length 2'''. 
|| The default length of second pendulum is '''1 m.''' 

|- 
|| Move the cursor on '''Mass 2.''' 
|| Default mass is '''0.50 kg.''' 

|- 
|| Click and drag the blue pendulum to '''60 degrees'''. 
|| Drag the blue pendulum to '''60 degrees''' and allow it to oscillate. 

|- 
|| Click and drag the red pendulum to '''60 degrees.''' 
|| Similarly, drag the red pendulum. 

|- 
|| Move the cursor on the '''Acceleration''' and ''' Velocity''' box. 
|| Note that green colour is for '''Velocity '''vector. 

And yellow is for '''Acceleration.''' 

|- 
|| Click on the '''Velocity '''check box. 
|| Select '''Velocity '''check box. 

|- 
|| Click on the '''slow '''radio button. 
|| Select the S'''low '''radio button to observe the velocity vector carefully. 

|- 
|| Move cursor on '''green''' colour arrow. 
|| Here, we observe that velocity is maximum at its mean position. 

It decreases at the extreme positions. 

This is due to maximum kinetic energy at the mean position. 

|- 
|| Click on the acceleration check box. 
|| Similarly, let us select acceleration vector and observe the change in acceleration. 

|- 
|| '''Slide Number 14''' 

'''Assignment ''' 
|| As an assignment, 

Explain why acceleration is maximum at extreme positions? 

|- 
|| Click on the '''Reset''' button. 
|| Click on '''Reset '''button to reset the '''simulation.''' 

|- 
|| Point to the Blue pendulum. 
|| Using the pendulum, we will compare calculated and measured Time period for different length. 

|- 
|| '''Slide Number 15''' 

'''Tabular column''' 
|| Let us make a tabular column for 

Length '''L''', 

Time period '''T''' (Calculated) and 

Time period '''T''' (Measured). 

|- 
|| '''Slide Number 16''' 

'''Formula for time period.''' 

We can calculate the time period using formula 

'''T=2π√(l/g)''' 

Where '''‘l’''' is the length and '''‘g’''' is acceleration due to gravity. 

Value of '''g=9.81m/s^2''' 
|| We can calculate the time period using formula 

'''T=2π√(l/g)''' 

Where '''‘l’''' is length and '''‘g’''' is acceleration due to gravity. 

Value of '''g=9.81 m/s^2''' 

|- 
|| Click on the '''Period Timer''' check box from the left bottom grey colour box. 
|| Select '''Period Timer'''. 

On the right side of the screen a '''Period Timer''' appears. 

|- 
|| Point to length slider. 
|| Note down '''0.70 m''' in the length column. 

|- 
|| '''Slide Number 17''' 

'''Tabular column.''' 
|| Here I have already calculated the time period using the formula. 

We will measure the time period from the '''simulation.''' 

|- 
|| Click and drag the '''pendulum'''. 
|| Now click and drag the pendulum to '''40 degrees'''. 
|- 
|| Click on the start button of '''Period Timer'''. 
|| Click on the start button of the '''Period Timer'''. 

Value for time period appears on the screen. 

|- 
|| '''Slide Number 18''' 

'''Tabular column''' 
|| Note the time period in the measured column. 

|- 
|| Click and drag the '''Length''' slider to '''0.60 m'''. 
|| Now change the length to '''0.60 m'''. 

|- 
|| Click on the '''Period Timer'''. 
|| Again click on the '''Period Timer'''. 

|- 
|| '''Slide Number 19''' 

'''Tabular column.''' 
|| Note the value in the table. 

|- 
|| '''Slide Number 20 + 21 ''' 

'''Assignment ''' 
|| As an assignment, 

* Change the lengths of the pendulum to '''0.50 m, 0.40 m, and 0.30 m.''' 
* Note down the measured Time period. 
* Calculate the time period using the formula. 
* Compare the calculated and measured time period values. 

|- 
|| Click on '''Reset''' button. 
|| Next '''Reset '''the '''simulation.''' 

|- 
|| Click and drag the pendulum to '''30 degrees.''' 
|| Drag the pendulum to '''30 degrees '''to oscillate. 

|- 
|| Point to '''Gravity.''' 
|| Note that '''acceleration due to gravity on Earth is 9.81 meter per second square.''' 

|- 
|| Click on the drop down list below '''Gravity''' to select '''Jupiter.''' 
|| Now select '''Jupiter''' from the drop down list. 

|- 
|| Point to pendulum. 
|| Observe the change in oscillations of the pendulum. 

|- 
|| Point to '''Gravity''' value. 
|| Note that value of acceleration due to gravity on '''Jupiter''' is more than that on '''Earth.''' 

|- 
|| '''Slide Number 22''' 

'''Assignment.''' 
|| As an assignment, 
 
Observe the oscillations on other celestial bodies. 

|- 
|| 
|| Let us summarise 

|- 
|| '''Slide Number 23''' 

'''Summary.''' 
|| In this tutorial, we have demonstrated, 

How to use '''Pendulum lab PhET simulation.''' 

|- 
|| '''Slide Number 24''' 

'''Summary.''' 
|| Using this '''simulation''', we have, 

Described Simple Harmonic Motion 

Demonstrated oscillations of a pendulum''' ''' 

Investigated the factors that affect the oscillations of a pendulum 

|- 
|| '''Slide Number 25''' 

'''Summary.''' 
|| Demonstrated how energy is conserved during oscillations 

Demonstrated the oscillations of a pair of pendulums 

Observed the oscillations on other celestial bodies 

|- 
|| '''Slide Number 26''' 

'''About Spoken Tutorial project.''' 
|| The video at the following link summarizes the Spoken Tutorial project. 

Please download and watch it. 

|- 
|| '''Slide Number 27''' 

'''Spoken Tutorial workshops.''' 
|| The&nbsp;'''Spoken Tutorial Project&nbsp;'''team, 

conducts workshops using spoken tutorials and 

gives certificates on passing online tests. 

For more details, please write to us. 

|- 
|| '''Slide Number 28''' 

'''Forum for specific questions:''' 

Do you have questions in THIS Spoken Tutorial? 

Please visit this site 

Choose the minute and second where you have the question. Explain your question briefly 

Someone from our team will answer them 
|| Please post your timed queries in this forum. 

|- 
|| '''Slide Number 29''' 

'''Acknowledgements.''' 
|| This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching. 
|- 
|| '''Slide Number 30''' 

'''Acknowledgement''' 
|| Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India. 

More information on this mission is available at this link. 

|- 
|| 
|| This is Himanshi Karwanje from IIT-Bombay. 

Thank you for joining. 
|-
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