## Friday, March 7, 2014

### EJSS kinematics in y model

EJSS Kinematics in Y direction Model by lookang

based on models and ideas by

1. lookang http://weelookang.blogspot.sg/2013/12/ejss-free-fall-model.html
2. Fu-Kwun and lookang http://weelookang.blogspot.sg/2010/09/ejs-open-source-bouncing-ball-with-drag.html  and http://weelookang.blogspot.sg/2010/06/ejs-open-source-kinematics-java-applet.html
3. Andreu Glasmann, Wolfgang Christian, and Mario Belloni http://www.compadre.org/osp/items/detail.cfm?ID=13050
4. template objects from lookang http://weelookang.blogspot.sg/2013/12/ejss-kinematics-model.html
 https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_freefall01/freefall01_Simulation.html source: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_src_freefall01.zip EJSS Kinematics in Y direction Model by lookang, based on models and ideas from Fu-Kwun, Andreu Glasmann, Wolfgang Christian, and Mario Belloni authors: lookang, Fu-Kwun, Andreu Glasmann, Wolfgang Christian, and Mario Belloni author of EJS 5: Paco.

## The equation that model the motion of the ball is:

$\frac{\delta y}{\delta t} = v_{y}$

$\frac{\delta v_{y}}{\delta t} = a_{y}$

 https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_freefall01/freefall01_Simulation.html source: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_src_freefall01.zip EJSS Kinematics in Y direction Model by lookang, based on models and ideas from Fu-Kwun, Andreu Glasmann, Wolfgang Christian, and Mario Belloni authors: lookang, Fu-Kwun, Andreu Glasmann, Wolfgang Christian, and Mario Belloni author of EJS 5: Paco.

 taken from http://psychology.wikia.com/wiki/File:Soccer_ball.svg http://commons.wikimedia.org/wiki/File:Soccer_ball.svg

This EjsS  Free Fall was developed using the Easy Java/JavaScript Simulations (EjsS) version 5. Although EjsS is a Java program, it can create stand alone JavaScript programs that run in almost any PC or tablet.

## Difference between Speed and Velocity:

students are generally confused by the difference between speed and velocity, and it is made harder when teachers use speed and velocity interchangeably.

To make learning easier, the following conditions or definitions are programmed into the model:

when

$v_{+} - v_{-} = 0$ means velocity is unchanged

$|v_{+}| - |v_{-}| = 0$ means speed is unchanged

$v_{+} - v_{-} > 0$ means velocity is increasing

$|v_{+}| - |v_{-}| > 0$ means speed is increasing

$v_{+} - v_{-} < 0$ means velocity is decreasing

$|v_{+}| - |v_{-}| < 0$ means speed is decreasing

## Calculation to determine acceleration:

the calculation is based on the definition and it illustrates the usefulness of definition is real life:

$a_{measured} = \frac{v_{+}-v_{-}}{\delta t}$

## Criteria for uniform motion:

though not include into the model yet, uniform motion is defined as:

$uniform motion => a = 0$

5. checkboxes for $y$ vs t, $v_{y}$ vs t and $a_{y}$ vs t graphs