EJSS Object on Plane Model for Primary School Inquiry showing Friction versus time

reference:
  1. EJS Static and Kinetic Friction on Incline Plane Model by Francisco Esquembre and lookang http://weelookang.blogspot.sg/2014/04/ejs-static-and-kinetic-friction-on.html
  2. Sliding Down an Incline Plane Model by Francisco Esquembre http://www.compadre.org/osp/items/detail.cfm?ID=9973
http://weelookang.blogspot.sg/2014/05/ejss-object-on-plane-model-for-primary.html
https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_frictionprimaryfvt/frictionprimaryfvt_Simulation.html
source: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_src_frictionprimaryfvt.zip
author: Francisco Esquembre and recreated on EJSS by lookang


The other derived and similar models

EJSS Static and Kinetic Friction on Incline Plane Model
http://weelookang.blogspot.sg/2014/04/ejss-static-and-kinetic-friction-on.html
https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_friction/friction_Simulation.html
source: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_src_friction.zip
author: Francisco Esquembre and recreated on EJSS by lookang
EJSS Static and Kinetic Friction on Incline Plane Model
http://weelookang.blogspot.sg/2014/04/ejss-static-and-kinetic-friction-on.html
https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_friction/friction_Simulation.html
source: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_src_friction.zip
author: Francisco Esquembre and recreated on EJSS by lookang

EJS Static and Kinetic Friction on Incline Plane Model
http://weelookang.blogspot.sg/2014/04/ejs-static-and-kinetic-friction-on.html
https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejs_model_SlidingDownAnInclinedPlanewee.jar
author: Francisco Esquembre and remixed by lookang

Model description by Paco:

Block sliding down an inclined plane

A stone block is lying on an inclined plane.

Initially, the component of gravity along the plane surface, mgcos(θ)=Ftangent , is balanced by the force caused by static friction fstatic, which is proportional to the normal to the plane, N .
The model assume the mass of the block is m = 1 kg,

W=mg

where W is the weight and g is the gravitational constant of 9.81 m/s^2

In equilibrium,

F=0

mgsin(θ)fstatic=0

mgcos(θ)N=0

In this model,

Ftangent=mgsin(θ)

Fnormal=mgcos(θ)

However, the modulus of this force fstatic cannot exceed a limit value of  μ|N|  where μstatic is the static friction coefficient between the block and the plane.


fstaticμstaticN in the direction negative of the velocity vector.

In this model, when velocity = 0,

fstaticmax=μstaticN and

fstatic=Math.min(mgsin(θ),fstaticmax) 

since fstatic cannot be greater than mgsin(θ) nor μstaticN

When the user increases the slope of the plane θ by dragging slider of angle θ , Ftangent ends up being larger than this limit and the block slides down the plane with kinetic friction present fkinetic=μkineticN .

In this model, when velocity not equal to zero,

fkinetic=μkineticN .

The force caused by static friction is replaced by a (smaller) force of dynamic (or kinetic) friction fkinetic, given by μkinetic|N| (where μkinetic is the dynamic friction coefficient between the block and the plane, which is smaller then the static one, μstatic).

Condition for hint:

if (velocity = 0 and and only and totalForce(t,x,v) = 0), hint statetext = " in equilibrium,..."
else if (velocity = 0 and and only and totalForce(t,x,v) != 0) hint statetext = " NOT in equilibrium,..."
else if (velocity != 0) hintstatetext= " NOT in equilibrium and in motion..."

Determine direction of motion and direction of friction

if (v===0){
  directionOfMotion=0;
  }
  else if (v<0){
    directionOfMotion=-1;
    }
    else if (v>0){
    directionOfMotion=+1;
    }

Custom function:

function totalForce(time,position,velocity) {
 if (velocity!==0) return Ft+directionOfMotion*dynamicFriction; // in motion
  return Math.max(0,staticFriction+Ft); // not in motion
}

changes made:

  1. re-implemented on EJSS
  2. added a scaleforce to draw the forces to user's choice
  3. made the static and kinetic friction drawn from same vector as visible===true was buggy
  4. added more hints to make explicit in equilibrium and not in equilibrium when net force.
  5. made the color dynamic with change in static to kinetic
  6. added paco as co-author as the EJS codes came from the man :)
  7. customized to nelson's request added menu for rubber, wood, iron and glass
  8. added mass inputs
  9. added graph of friction versus time




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Labels: ejss NEWTONIAN MECHANICS