# How do I calculate weight?

• I'm trying to make a trajectory view for my golf game. I'm doing this simply by firing smaller balls from the current position of the ball with the same physics calculation for firing.

hence the problem, this does not give the same result.

how do I calculate the weight of a circle in construct? The main ball is 18*18, the smaller sprite is 9*9,

by my math (which is poor) this should result in the bigger ball being just over 4 times larger in size.

giving the smaller ball this density gets close. but since it is a precision game close isn't good enough.

anyone with better math skillz then mine who can tell me what I'm doing wrong here?

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• I havent used physics but

I think you just need to make sure both balls are the same 2D mass.

so area ball1 x density ball1 = area ball2 x density ball2

So to find the density of ball 2 then

( area ball 1 x density ball1) / area ball 2 = density ball 2

as i said though havent used physics dont know how it measures area (is it the area of the collision box or the actual sprite?)

but anyway regardless the above should apply.

• Totally agree NetOne, as this is how I calculated it.

problem seems to be that I don't really know the area. it uses the collision box, but I use the circle collision box from the physics behavior. straightforward method would be that it uses the entire sprite and therefor give a diameter of 18 pixels of the large one and 9 pixels on the smaller one.

but this does not seem to be the case.

• Nevermind, I'm an idiot who doesn't know how to copy settings from one sprite to another. problem was linear damping was slightly off. resulting in slightly different results