Java simulations created by EJS can be found at [url=http://www.phy.ntnu.edu.tw/ntnujava/index.php?action=collapse;c=3;sa=expand#3]Easy java simulation category[/url].

It is very easy to include air drag into ejs.

Just add air drag terms into evolution equations in ejs.

For this simulation : The drag force is propotional to V[sup]2[/sup]

For projectile motion you should have the following equations in EJS evolution page:

dx/dt=vx;

dy/dt=vy;

dvy/dt=-g;

If you want to add drag force like this one. In this model, the drag force is proportional to F=-b*V[sup]2[/sup], where b is the drag force coefficient.

Fx=-b*V[sup]2[/sup]*(vx/|V|)=-b*vx*|V|;

Fx=-b*V[sup]2[/sup]*(vy/|V|)=-b*vy*|V|;

You should modify the evolution equations to the following:

dx/dt=vx;

dy/dt=vy;

dvx/dt=-b*Math.sqrt(vx*vx+vy*vy)/m*vx;

dvy/dt=-b*Math.sqrt(vx*vx+vy*vy)*vy/m-g;

The following is EJS version of air drag simulation.translate strings in simulation to different language format before download

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