So there it is me trying to program some simple physics for flying ball. I have done some research and generally I was always understanding physics very well. But what is happening in my application is not understandable for me, even tho I have checked everything twice and I think everything should have worked good.(adsbygoogle = window.adsbygoogle || []).push({});

So my physics is very simple, only gravity and air resistance, no spinning of ball etc.

My ball has few attributes, which are:

-position(in meters, I also assume that one 1px==1m),

-mass(in kg),

-radius(in meters),

-speed, which is basically a vector with direction and value (in m/s).

In physics engine I assume g=9.81 [m/s^2] and air density of q=1.2041 [kg/m^3].

Now thats how I calculate where to move the ball:

(1)I move the ball according to its actual speed vector.

(2)I calculate forces on the ball:

(3)Now I can calculate acceleration of the ball by simply deviding Ft by mass of the ball (a=Ft/m) and I keep a as a vector(just like speed) with value calculated and appropriate direction calculated (I have checked it and the direction of a is calculated correctly).

- gravity: Q= g*m [thats a vector always directed downwards]
- air resistance: F= (0.47*q*A*v^2)/2 where:

- F is air resistance [N]
- 0.47 is drag coefficient for the ball (found on wiki)
- q is density of air
- A is the cross-sectional area of the ball
- v is speed of the ball
- the air resistance is always directed opposite to actual speed
- total force (Ft) on the ball by adding both vectors for Q and F

(4)I update the speed of the ball V1=V+a*t (time was 1 sec, but i still multiply it by time in case I want to change time intervals). I do that by simply adding 2 vectors (V and a) together.

My problem is: I tested it on a ball with:

-some start position with doesnt matter here

-mass of 0.2 [kg],

-radius of 0.01 [m],

-start speed of 200 [m/s] 45% upwards

Now the ball fly and it looks good. But when I change just the mass to lets say 0.6kg the ball actually fly further, like much further... Despite the fact that air density and gravity seems to be bigger.

Am I calculating something wrong? Or is that how it supposed to be?

Thanks for your help.

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# Calculations for flying ball

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