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

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Time Narration
Slide Number 1

Title Slide

Welcome to this spoken tutorial on Simple Machines.
Slide Number 2

Learning objective

In this tutorial we will demonstrate,

Pulley system

Lever Principle Apps.

Slide Number 3

System Requirements

Here I am using,

Ubuntu Linux OS version 16.04

Firefox Web Browser version 62.0.3

Slide Number 4

Pre-requisites

To follow this tutorial, learner should be familiar with topics in basic physics.
Slide Number 5

Learning Goals

Using these Apps we will,
  • Show how a pulley system works.
  • Calculate the necessary force to pull the load.
  • Show the working of a lever principle.
  • Explain how to achive a balance condition.
Slide Number 6

Pulley A pulley is a simple machine that is used to lift the heavy objects.

We can either use a single pulley or a combination of pulleys.


For example pulleys can be used in

wells, escalators, rock climbing, flag poles and others.


First we will define a pulley

A pulley is a simple machine that is used to lift heavy objects.


We can either use a single pulley or a combination of pulleys.


For example pulleys can be used in

wells, escalators, rock climbing, flag poles and others.

Slide Number 7

Link for Apps on physics App

https://www.walter-fendt.de/html5/phen


Use the given link to download the Apps.

https://www.walter-fendt.de/html5/phen


Point to the file in the downloads folder I have already downloaded Apps on Physics to my Downloads folder.
Point to html5phen folder in the Downloads folder. After downloading, html5phen folder appears in the Downloads folder.


Double-click on html5phen folder.


Point to the ph and phen folders.

Double-click on html5phen folder.


We see two folders namely ph and phen in the html5phen folder.


Double-click on phen folder.


Point to Apps in java script format and htm format.

Now double-click on the phen folder.


In this folder, we see Apps in java script format and htm format.

Point to the htm formats Apps. We will use the Apps with htm file format.


Point to Pulley system, Lever Principle Apps. To open Pulley system press Ctrl+F keys and type Pulley system.
Right click on pulleysystem_en.htm file.


Select the option Open With Firefox web Browser option.


Cursor on the App.

Right click on pulleysystem_en.htm file.


Select the option Open With Firefox web Browser.


Pulley System App opens in the browser.

Point to the App interface.

Move the cursor to the green panel.

Move the cursor to the yellow panel.

The App interface opens with two panels.

A green coloured panel to change and display parameters.

An yellow panel with a pulley system.

Move the cursor on the load – pulley-rope. Here we can see that a load is attached to the pulley through a rope.
Point to the Springscale. We can either raise or lower the load with the help of a Springscale.
Show the movement of the Springscale by the pressed mouse.


Point to the values in the right panel.

Click and drag the mouse to raise or lower the load.

Observe that there is no changes in the values in the right panel.

This is because the necessary force required to drag the load remains the same.

Click on drop down list to show the numbers of pulleys On the top of the green panel you can see a drop down list of pulleys.

List has 2, 4, and 6 pulleys systems.

Point to the Weight.


Edit and show 1 value (write 20)

The weight of the load is displayed in the white box.


The default weight of the load is 14 Newton.


We can change value of weight from 1 Newton to 40 Newton.

Move the cursor to show the Weight of the loose pulleys. We can change the Weight of the loose pulley in this box.
Point to the black pulleys. This is the toatal weight of the 4 pulleys.
Point to show Necessary force. Next the Necessary force used to lift the load is calculated using the App.

Point to Springscale and

Force vectors.

At the bottom of the green panel we have Springscale and Force vectors radio buttons.


By default Springscale is selected.

Now let us demonstrate the working of the pulley.
Point to the load.


Point to the 4 sections of the rope.


Point to Necessary force.

Observe that weight of 20 Newton is hanging from the 4 pulley sections of the rope.


Each section of the rope has one forth of the total weight.

In the App the force required to raise the weight in the air is calculated.

Slide Number 8

Necessary force

F= (Wl+ Wp)/4

Wl is Weight of the load.

Wp is Weight of the loose pulley.

The Necessary force is calculated using the given formula.

F= (Wl+ Wp)/4

Wl is weight of the load.

Wp is weight of the loose pulley.

Edit the Weight of the loose pulley to 20 Newton.

Point to Necessary force

Now change the Weight of the loose pulley to 20 Newton.

Observe that the Necessary force is changed to be 10 Newton.

Change the Weight of the load to 30 Newton. Next change the weight of the load to 30 Newton.

Point to the Weight of the loose pulley.


Highlight the last line from the App.

Note that as we change the weight of the load to 30Newton, weight of the loose pulley has changed to 10 Newton.


This is because the Springscale’s limit is 10 Newton.

Values more than 10Newtonare automatically changed to 10Newton.

Slide Number 9

Assignment

Change the weight of the load to 25 N and weight of the loose pulley to 10 N and calculate the necessary force.

Verify your answer from the App.


As an assignment,

Change the weight of the load to 25 N and Weight of the loose pulley to 10 N and calculate the necessary force.

Verify your answer from the App.


To open Lever Principle App right-click on lever_en.htm and Open With Firefox Web Browser. Next we will move on to Lever Principle App.

To open Lever Principle App right-click on lever_en.htm and Open With Firefox Web Browser.

Point to the screen(highlight the sentence from the App.) This app shows a symmetrical lever with some mass pieces.

Each mass piece weighs 1 Newton.

Scroll down to show the lever principle.(pink box) At the bottom of the interface Lever Principle is defined.

A lever is in balance if the total left side torque is equal to the total right side torque.

Scroll up to see the App.


Point to the lever arm.

Observe that the lever arm is shown by green and yellow rectangles.

Length of each rectangle is 0.10 m.

Point to the torque measured. At left bottom of the screen torque is calculated.
Slide Number 10

Torque

Torque is the twisting force that tends to cause a rotation.

The point where the object rotates is aixs of rotation.

Torque is the twisting force that tends to cause rotation.

The point where the object rotates is the axis of rotation.

Point to the fulcrum. In the App fulcrum is the axis of rotation.
Slide Number 11

Torque

(tau) τ = F r

F is a force applied by the load.

ris a perpendicular distance from the fulcrum.

Next we can calculate the torque using the formula.

(tau)τ = F* r⟂(perpendicular) .


Point to green and yellow rectangles. The green and yellow rectangles indicate perpendicular distances.
Remove one weight from the left side of the fulcrum. We can change the hanging weight by clicking and holding mouse.
Point to fulcrum.


Move the cursor to show the calculations.

Observe that now the lever is unbalanced.


This is because the torque between the two side is not same.

Point to 0.9 Nm. Notice that in the measured part the value of left side torque is reduced to 0.9 Nm

(Newton-meter).

In the text-box type. (What happens when hanging weights are removed from both the sides) What happens when hanging weights are removed from both the sides.
Point to the left side of the fulcrum. Next let us hang the weights at different distances to the left of the fulcrum.
Click and hold the mouse to add one weight on the third rectangle.

Continue to add two weights on the fourth rectangle.

One weight on the fifth rectangle.

Click and hold the mouse to add one weight on the third rectangle.

Add two weights on the fourth rectangle.

And one weight on the fifth rectangle.

Point to the lever. Observe that the lever is now unbalanced.
Point to the right side. Now let us add weights to the right side of the fulcrum to balance the lever.
Use pressed mouse to add the weights from

right to 1st rectangle.

Click and hold the mouse to add one weight to the first rectangle.
Hang the weight to 3rd, 4th, and 5th rectangles. Continue to add one weight to third, fourth and fifth rectangles.
Point to the lever. Notice that the lever is now balanced.
Slide Number 12

Assignment

If a blocks weigh 5 N is kept at 0.5 m, 3 N at 0.4 m and 2 N at 0.6 m from the fulcrum on the same side. How far must the other blocks of weighs 7 N should kept from the fulcrum in order to balance them.

As an assignment solve this numerical.


Let us summarise
Slide Number 13

Summary

Using these App we have * Observed how a pulley system works.
  • Calculated the necessary force to pull the load.
  • Observed the working of a lever principle.
  • Explained how to achive a balance condition.


Slide Number 14

License

These Apps are created by Walter-fendt and his team.

This video is released under CC-BY-NC-SA license.


These Apps are created by Walter-fendt and his team.

This video is released under CC-BY-NC-SA license.


Slide Number 15

About Spoken Tutorial project.


The video at the following link summarizes the Spoken Tutorial project.

Please download and watch it.

Slide Number 16

Spoken Tutorial workshops.


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 17

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

Slide Number 18

Forum for specific questions:


The Spoken Tutorial forum is for specific questions on this tutorial

Please do not post unrelated and general questions on them

This will help reduce the clutter

Template:Anchor With less clutter, we can use these discussion as instructional material.

Slide Number 19

Acknowledgement

Spoken Tutorial Project is funded by MHRD, Government of India.
This is Himanshi Karwanje from IIT-Bombay.

Thank you for joining.

Contributors and Content Editors

Karwanjehimanshi95, Madhurig, Nancyvarkey