Hi prof Hwang I modified project *v^2 in a physlets formula for air resistance and come to my mind idea to add slider for control in angle(theta) So i add slider position up name is theta and back to equation and typing it vx=V*Math.cos(angle/90); vy=V*Math.sin(angle/90); After i back again to slider theta and add the following values in image gif that I'm attach But I'm sure have wrong because when i drag slider theta to value less 40 simulation not work I don't know why Could you check prof what wrong i make Thanks I attach also jar,,XML files of simulation

I do first solution that is i use variable pi=3.14159 in page basic. And equation: vx=V*Math.cos(angle*pi/180.); But i notice that arrow of velocity is down by way strange down more than normally,,cant drag arrow easy for degree i want,,movement of mass slowly. And if i use less value on slider theta simulation no work. I don't know what wrong i do. And i want say another point when i change value of pi from 3.14159 to Math.PI happend diffrent movement i can say is more good than i use pi=3.14159. But problems about velocity arrow,,hard control in drag slider of theta and when less value on slider theta simulation no work is the same no change may is have some diffrent in movement become more fast. I upload applet for you check prof by first value pi=3.14159. Applet prof

Second code i modified but first code is original I'm no change And i modified variable pi=3.14159 to PI=3.14159 When i use code you post prof ejs consul give 7 error so i back to Original code And post for you check what wrong i made more. About a nother problems is the same (velocity is slowly),,,when i drag slider to value less than 30 degree simulation no work. Applet after solve problem arrow of velocity

Yes prof But I'm try solve problem about when i drag theta less than 30 degree Simulation not work i don't know where is wrong can you fix this wrong prof please Thanks

The above simulation assume air drag is model with where is the magnitude of the velocity.

Nomally, for high speed projectile, the force is proportional to velocity square. i.e. Howeve,for slow projectile, the force is proportional to velocity. i.e. e.g. simulate a projectile moving under water.

User can adjust to find a suitable model for the case s/he want to simulated and compared with the real case under studied. And that can be one of the purpose for the above simulation. To find out a suitbale model for a real case.

Very well prof thanks for information's.but i notice a thing prof in applet when theta = 0.0 mass move to down I mean even i don't drag slider theta and I'm just press play without drag theta simulation work but what is strange Is mass work and fall to down My ask how theta 0.0 and mass fall down i think mass should be move direct or not move but Is moving down i will upload applet for you check prof

When the initlal velocity of the projectile is in the horizontal: Then it will move with constant speed in the horizontal direction and it will also have free fall motion in the vertical direction.

Why it should only move horizontally? or even not moving??? Let me know your argument!

I thought when i drag theta to 0.0 and initial V to 0.0 So we no have velocity or angle,so no have movement. I mean when it should move horizontally this if we drag only initial V without drag theta, So we will have velocity without angle in this case i think move horizontally. However prof thanks i understand your explain now I'm just try understand every thing about simulation

« Last Edit: June 15, 2010, 06:25:33 pm by ahmedelshfie »

You did not add any action when initial velocity slider were changed. I add _initialize() to the action. And it should work fine when you drag slider for V.

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