Difference between revisions of "PhET/C3/Pendulum-Lab/English"
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|| Point to the Blue pendulum. | || Point to the Blue pendulum. | ||
| − | || Using the pendulum, we will compare calculated and measured Time period for different | + | || Using the pendulum, we will compare calculated and measured Time period for different lengths. |
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Latest revision as of 15:57, 21 December 2018
| 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
Learning goals |
Using this simulation, we will,
|
| Slide Number 6
Learning goals |
|
| 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
Here, mechanical energy is conserved. |
| Slide Number 9
Link for PhET Simulation |
Use the given link to download the simulation. |
| 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 slidertowards 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 0.50kgin 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. |
| Cursor on the screen. | 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.
one, two, three, four, five, six, seven, eight, nine, ten. |
| 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 Stop 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 Intro 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 Slow 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 Period Timer instead of Period 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 Slow 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 lengths. |
| 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. |
| Cursor on interface. | 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 18
Tabular column |
Note the value in the table. |
| Slide Number 19
Assignment |
As an assignment,
|
| Slide Number 20
Assignment |
|
| 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 21
Assignment |
As an assignment,
Observe the oscillations on other celestial bodies. |
| Let us summarise | |
| Slide Number 22
Summary |
In this tutorial, we have demonstrated,
How to use Pendulum lab PhET simulation. |
| Slide Number 23
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 24
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 25
About Spoken Tutorial project |
The video at the following link summarizes the Spoken Tutorial project.
Please download and watch it. |
| Slide Number 26
Spoken Tutorial workshops |
The Spoken Tutorial Project team,
conducts workshops using spoken tutorials and gives certificates on passing online tests. For more details, please write to us. |
| Slide Number 27
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 28
Acknowledgements |
This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching. |
| Slide Number 29
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. |
