Balancing VectorForce based on object size

[descreetOP]

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I want the two balls to rise with the same speed, so changing the force according to their size.
I also tried changing the density, as you can see in the video.

[NOVEIGMA]

Multiply force by mass. This is literally high school level physics.

force = mass * acceleration
--acceleration must be constant for things to move at the same rate
--so if mass increases, force must also increase to keep the equation balanced
(force*2) = (mass*2) * acceleration

Here’s what that may look like in a script:

local ball = script.Parent
local vforce = ball:WaitForChild('VectorForce')

local acceleration: Vector3 = Vector3.new(3, 0, 0) --3 studs per second per second
vforce.Force = acceleration * ball.AssemblyMass