Newton's Second Law of Motion

xholonWorkbook.xml

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<!--Xholon Workbook http://www.primordion.com/Xholon/wb/ (C) Ken Webb Mon Feb 13 2012 14:16:08 GMT-0500 (EST)-->
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<Notes><![CDATA[
Khan Academy
------------
Title: Newton's Second Law of Motion
Description: Newton's Second Law of Motion:  F=ma
Url: http://www.khanacademy.org/video/newton-s-second-law-of-motion?playlist=Physics
InternalName: newton-s-second-law-of-motion
YoutubeId: ou9YMWlJgkE
Keywords: physics, newton, 2nd, second, law

My Notes
--------
- the constant velocity from the first law could be 0
- how does a net force effect a constant velocity?

the 2nd law
F = m * a
 - where F is a force, m is a mass, and a is an acceleration
 - acceleration is a vector
 - force is a vector

example
- a Brick floating in Space
- if you apply a net force to one side of the Brick (which might be a sum of several forces),
  then there will be a net acceleration in the same direction

- a is proportional to F
- the constant of proportionality is the object's mass
- Note: weight is a force, while mass says how much stuff there is
- unit of force is a "Newton" N = kg * m / s^2

a problem
- Brick with a mass of 2 kg
- F is 10 N to the right
- what is the acceleration?
- if the force doubles, then the acceleration doubles
  - this is part of Sal's example, so it could be part of a code example
- also, if you double the mass, then the acceleration will be only half

]]></Notes>

<script implName="lang:python:inline:"><![CDATA[
# http://ideone.com/r92n6
m = 2
f = 10
a = f / m
print "a = "   str(a)   " meters per second squared"
]]></script>

<script implName="lang:javascript:inline:"><![CDATA[
// sequential code
m = 2;     // mass in kg
f = 10;    // force F in N
a = f / m; // acceleration in m/s^2
print("a = "   a   " meters per second squared");

// a function, that can be pasted into the browser address bar
// try doubling the force, and then doubling the mass, as mentioned by Sal
//javascript:(function(m,f){a=f/m;alert("a=" a "m/s^2");})(2.0,10.0)
]]></script>

<_-.XholonClass>

  <!-- domain objects -->
  <PhysicalSystem/>
  <Brick/>
  
</_-.XholonClass>

<xholonClassDetails>
  <Brick>
    <port name="m" connector="#xpointer(Mass)"/>
    <port name="f" connector="#xpointer(Force)"/>
    <port name="a" connector="#xpointer(Acceleration)"/>
  </Brick>
</xholonClassDetails>

<PhysicalSystem roleName="space">
  <!-- 2 bricks -->
  <Brick roleName="scalar">
    <!-- scalar version, where the direction is assumed to be in the positive x direction (to the right) -->
    <Mass>2.0 kg</Mass>
    <Force>10.0 N</Force>
    <Acceleration>0.0 m/s^2</Acceleration>
  </Brick>
  <Brick roleName="2D vector">
    <!-- 2D vector version with x and y components (Sal said that a and F are vectors) -->
    <Mass>2.0 kg</Mass>
    <Force>10.0 0.0 N</Force>
    <Acceleration>0.0 0.0 m/s^2</Acceleration>
   </Brick>
</PhysicalSystem>

<Blockbehavior implName="lang:python:inline:"><![CDATA[
# TODO
]]></Blockbehavior>

<Brickbehavior implName="lang:javascript:inline:"><![CDATA[
  // paste in as a last child of either the scalar or 2D vector Brick
  if (contextNodeKey.roleName == "scalar") {
    a.setVal(f.val / m.val);
    println(a);
  }
  else { // vector
    var magnitudeA = f.val / m.val;
    a.setVal(""   magnitudeA   " 0.0 "   a.unit);
    println(a);
  }
]]></Brickbehavior>

<Blockbehavior implName="lang:bsh:inline:"><![CDATA[
// TODO
]]></Blockbehavior>

<Blockbehavior implName="lang:jruby:inline:"><![CDATA[
# TODO
]]></Blockbehavior>

<Blockbehavior implName="lang:groovy:inline:"><![CDATA[
// TODO
]]></Blockbehavior>

<SvgClient><Attribute_String roleName="svgUri"><![CDATA[data:image/svg xml,

]]></Attribute_String><Attribute_String roleName="setup">${MODELNAME_DEFAULT},${SVGURI_DEFAULT}</Attribute_String></SvgClient>

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