Apps-On-Physics/C2/Simple-Machines/English-timed

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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

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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.

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