Apps-On-Physics/C2/Simple-Machines/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:01 | Welcome to this spoken tutorial on Simple Machines. |
| 00:05 | In this tutorial we will learn to, |
| 00:08 | Simulate the working of a pulley system. |
| 00:11 | Calculate the necessary force to pull the load. |
| 00:14 | Achieve a balance condition for the lever. |
| 00:18 | Calculate the torque. |
| 00:21 | Here I am using, Ubuntu Linux OS version 16.04
Firefox Web Browser version 62.0.3 |
| 00:33 | To follow this tutorial, learner should be familiar with topics in basic physics. |
| 00:41 | First we will define a pulley. |
| 00:44 | A pulley is a simple machine that is used to lift heavy objects. |
| 00:49 | We can either use a single pulley or a combination of pulleys. |
| 00:54 | For example pulleys can be used in wells, escalators, rock climbing, flag poles and others. |
| 01:02 | Use the given link to download the Apps. |
| 01:07 | I have already downloaded Apps on Physics to my Downloads folder. |
| 01:12 | In this tutorial we will use, Pulley system and Lever Principle Apps. |
| 01:19 | After downloading, html5phen folder appears in the Downloads folder. |
| 01:25 | Double-click on html5phen folder. |
| 01:29 | We see two folders namely ph and phen. |
| 01:34 | Now double-click on the phen folder. |
| 01:37 | In this folder, we see the Apps in java script and htm format. |
| 01:43 | We will use the Apps with htm file format. |
| 01:47 | To open the Pulley system app, press Ctrl+F keys simultaneously. |
| 01:54 | In the search bar type Pulley system. |
| 01:58 | Right click on pulleysystem_en.htm file. |
| 02:04 | Select the option Open With Firefox web Browser.
Pulley System App opens in the browser. |
| 02:13 | The App interface opens with two panels. |
| 02:17 | A yellow panel with a pulley system and |
| 02:20 | A green panel to change and display parameters. |
| 02:25 | In the yellow panel, notice that a load is attached to the pulley with the help of a rope. |
| 02:33 | We can either raise or lower the load using a Springscale. |
| 02:38 | Click and drag the mouse to raise or lower the load. |
| 02:43 | Observe that there is no change in the value on the right panel. |
| 02:48 | This is because the necessary force required to drag the load remains the same. |
| 02:55 | On the top of the green panel you can see a drop down list of pulleys.
List has 2, 4, and 6 pulley systems. |
| 03:07 | The weight of the load is displayed in the white box. |
| 03:12 | The default weight of the load is 14 Newton. |
| 03:16 | We can change the value of the weight from 1 Newton to 40 Newton. |
| 03:22 | We can change the Weight of the loose pulley in this box. |
| 03:27 | This is the total weight of the 4 pulleys. |
| 03:31 | The Necessary force used to lift the load is calculated using the App. |
| 03:36 | At the bottom of the green panel we have Springscale and Force vectors radio buttons. |
| 03:43 | By default Springscale is selected. |
| 03:47 | Let us demonstrate the working of the pulley. |
| 03:51 | Observe that weight of 20 Newton is hanging from the 4 pulley sections of the rope. |
| 03:58 | Each section of the rope has one fourth of the total weight. |
| 04:03 | In the App force required to raise the weight in air is calculated. |
| 04:10 | The Necessary force is calculated using formula.
F= (Wl+ Wp) upon 4 |
| 04:18 | Wl is weight of the load.
Wp is weight of the loose pulley. |
| 04:26 | Now change the Weight of the loose pulley to 20 Newton. |
| 04:31 | Observe that the Necessary force is changed to 10 Newton. |
| 04:36 | Next change the weight of the load to 30 Newton. |
| 04:40 | observe that the weight of the loose pulley has changed to 10 Newton. |
| 04:46 | This is because the Springscale’s limit is 10 Newton. |
| 04:51 | Values more than 10 Newton are automatically changed. |
| 04:57 | As an assignment, Change the weight of the load to 25 Newton and weight of the loose pulley to 10 Newton. |
| 05:06 | Calculate the necessary force and verify your answer from the App. |
| 05:12 | Next we will move on to Lever Principle App. |
| 05:16 | To open Lever Principle App right-click on lever_en.htm file and Open With Firefox Web Browser. |
| 05:27 | This App shows a symmetrical lever with some mass pieces. |
| 05:32 | Each mass piece weighs 1 Newton. |
| 05:36 | At the bottom of the interface Lever Principle is defined. |
| 05:41 | A lever is in balance if the total left side torque is equal to the total right side torque. |
| 05:48 | Observe that the lever arm is shown by green and orange rectangles. |
| 05:54 | Length of each rectangle is 0.10 meter. |
| 05:59 | At the bottom left of the screen torque is calculated. |
| 06:05 | Torque is the twisting force that tends to cause a rotation. |
| 06:10 | The point where the object rotates is the axis of rotation. |
| 06:16 | In the App fulcrum is the axis of rotation. |
| 06:21 | We can calculate the torque using the formula.
(tau)τ = F x r⟂(perpendicular). |
| 06:29 | Green and orange rectangles indicate perpendicular distances. |
| 06:35 | We can change the hanging weight by clicking and holding the mouse. |
| 06:40 | Observe that, the lever is unbalanced. |
| 06:44 | This is because torque on both the sides is not same. |
| 06:49 | Notice that the value of left side torque is reduced to 0.9 Nm
(Newton-meter). |
| 06:56 | What happens when hanging weights are removed from both the sides. |
| 07:01 | Let us hang the weights at different distances to the left of the fulcrum. |
| 07:07 | Click and hold the mouse to add one weight on the third rectangle. |
| 07:13 | Add two weights on the fourth rectangle.
And one weight on the fifth rectangle. |
| 07:21 | Observe that the lever is now unbalanced. |
| 07:25 | Let us add weights to the right side of the fulcrum to balance the lever. |
| 07:31 | Click and hold the mouse to add one weight to the first rectangle. |
| 07:37 | Continue to add weights to third, fourth and fifth rectangles. |
| 07:43 | Notice that the lever is now balanced. |
| 07:48 | As an assignment solve this numerical. |
| 07:53 | Let us summarize |
| 07:55 | In this tutorial we have,
Simulated the working of a pulley system. |
| 08:01 | Calculated the necessary force to pull the load. |
| 08:05 | Achieved a balance condition for the lever. |
| 08:09 | Calculated the torque. |
| 08:12 | These Apps are created by Walter-fendt and his team. |
| 08:17 | The video at the following link summarizes the Spoken Tutorial project.
Please download and watch it. |
| 08:25 | Spoken Tutorial Project team, conducts workshops using spoken tutorials and gives certificates on passing online tests.
For more details, please write to us. |
| 08:39 | Do you have questions in THIS Spoken Tutorial?
Please visit this site |
| 08:45 | Choose the minute and second where you have the question. Explain your question briefly |
| 08:51 | The Spoken Tutorial project will ensure an answer. You will have to ask questions. |
| 08:59 | The Spoken Tutorial forum is for specific questions on this tutorial |
| 09:04 | Please do not post unrelated and general questions on them
This will help reduce the clutter |
| 09:12 | With less clutter, we can use these discussion as instructional material. |
| 09:18 | Spoken Tutorial Project is funded by MHRD, Government of India. |
| 09:24 | This is Himanshi Karwanje from IIT-Bombay.
Thank you for joining. |
