View source for Step/C2/Add-Forces-and-Interactions/English

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| style="border-top:0.002cm solid #000000;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| <center>'''Visual Cue'''</center>
| style="border:0.002cm solid #000000;padding:0.097cm;"| <center>'''Narration'''</center>

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| style="border-top:0.002cm solid #000000;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| Slide 1
| style="border:0.002cm solid #000000;padding:0.097cm;"| Welcome to this tutorial on how to add forces 


and interactions in STEP.

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| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| Slide 2


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| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:0.002cm solid #000000;padding:0.097cm;"| In this tutorial we will look at how to add forces.

Click on Applications, Education and scroll down to STEP to open it

This is where we will open STEP

For an introduction to STEP, please see www.spoken-tutorial.org

In this tutorial, I have worked on Ubuntu version 10.04 LTS and STEP version 0.1.0

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| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| Slide 5


Slide 6


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Slide 8


Slide 9
| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:0.002cm solid #000000;padding:0.097cm;"| In this lesson we will do the following:


Add springs


Simulate a linear motor


Simulate a circular motor


Add gravitational foces


Add a tracer

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| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| STEP Window
| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:0.002cm solid #000000;padding:0.097cm;"| Now we open the STEP window.


In ths window, we will now add a box.


The size of the box can be changed by 


clicking on the properties panel and changing its size here


or by clicking on the box and 


dragging along the outline


I have now changed the size of the box.

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| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| Adding a linear motor
| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:0.002cm solid #000000;padding:0.097cm;"| We will add a linear motor.


A linear motor provides a force that acts on the box


I have added a linear motor by clicking on it.


We can define the value of the force in the properties panel here.


Now we click on simulation.


We will see that the box moves with a uniform linear acceleration


given by the second law of motion.


The blue arrow indicates the direction of force and acceleration.


We also see that the box begins to rotate.


Why is this so?


This is so because the linear motor is not at the centre of mass of the box




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| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| File Save-As dialog box
| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:0.002cm solid #000000;padding:0.097cm;"| Now we will save the simulation as forces and interactions.


I am waiting for the Save-As Dialog box to open.


We will save this as Forces and Interactions.

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| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| Adding a circular motor
| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:0.002cm solid #000000;padding:0.097cm;"| We will now delete the linear motor.


A component can be deleted by clicking 


on the World Scene and deleting it.


We will now add a circular motor. 


I will delete this box and add it again So that I can add a circular motor.


Now I am adding a circular motor.


As usual, we can set the properties of the circular motor, the torque value, in


the properties panel.


Now we will click on simulate.


We will see that the box will rotate counter clockwise.


Now we will remove the box and the circular motor.


We can also delete the components by clicking on the world scene itself.


We click here and delete the circular motor.


We click here and delete the box.




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| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| Adding springs
| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:0.002cm solid #000000;padding:0.097cm;"| Now we will add two disks and connect them with a spring.


We will add Disk 1. We will add Disk 2. 


We will redefine the size of the disk.

And connect them with a spring.


We will now move one of these disks and simulate and see what happens.


I will give one of these disks a velocity in the positive x-direction.


When I click on simulate, I see that the spring moves back and forth.


Now we can stop the simlation.


We saw how two particles when connected by a spring behave.

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| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| Adding gravitational force
| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:0.002cm solid #000000;padding:0.097cm;"| Now we will delete these disks and spring and add particles and a gravitational force.


We will now add two particles to the world scene. 


We have added two particles. Now we will add the gravitational force.


The gravitational force has also been added to the world scene.


Now we will redefine the mass of the first particle to be 10<sup>10</sup> kg. 


You will notice that the red arrow indicates the direction of the gravitational 


force experienced by the second particle towards the first particle.


We will also redefine the color of the 1<sup>st</sup> particle now which can be done in the 


properties panel here. We will choose red for this simulation.


We will add a tracer to the second particle.


A tracer is a component you can add to a particle to track its trajectory or to 


track its behavior during a simulation. 


If you scroll down the palette, you will find the tracer here. 


So we will now add a tracer to the second particle.


Now we are ready to run our simulation.


You will notice that the 2<sup>nd</sup> particle moved towards 1<sup>st</sup> particle.


The red arrow gives the direction of the gravitational force and the blue arrow 


gives the direction of the velocity of the second particle. This blue line is the 


tracer that is attached to the second particle.


Now we have seen how gravitational force can be added to a simulation. 

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| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| 
| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:0.002cm solid #000000;padding:0.097cm;"| We will now review what we have learnt so far.


We have seen how to add springs, how to add a linear motor, how to add a 


circular motor and the gravitational forces and add a tracer.


Now we will look at an assignment to reinforce our understanding. 

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| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| Slide 10


Slide 11


Slide 12


Slide 13


Slide 14



| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:0.002cm solid #000000;padding:0.097cm;"| The assignment is as follows.

Introduce two charged particles

One is positive and the other is negative 

Add the electrostatic force

Simulate the interaction when both particles are at rest

Simulate when one of the particles is moving

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| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| STEP window. Charged particle simulation
| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:0.002cm solid #000000;padding:0.097cm;"| This is how the simulation will look when it is built.

We will click on simulate. This is how the simulation will behave when we 

build it. 

Please build this simulation for yourself to see how the coulomb force, the 

electrostatic force can be added in STEP. 

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| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| Slide 15


Slide 16


Slide 17
| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:0.002cm solid #000000;padding:0.097cm;"| I would like to acknowledge the Spoken Tutorial Project

which is a part of Talk to a Teacher Project

Supported by the National Mission on Education through ICT, MHRD, Government of India

More information:

http://spoken-tutorial.org/NMEICT-Intro




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| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:none;padding:0.097cm;"| Slide 18
| style="border-top:none;border-bottom:0.002cm solid #000000;border-left:0.002cm solid #000000;border-right:0.002cm solid #000000;padding:0.097cm;"| Thank you for joining me on this tutorial on how to add forces and interactions 

in STEP. This is Ranjani Ranganathan signing off. Thank you.

|}