Tonight I Saw the show with the Helium Filled Football myth on the dutch discovery channel, and I noticed a flaw in it. During their test in the NASA hanger, There was besides the weight of the ball one other factor which wasn't constant, namely the energy the ball starts with. The formula for it's kinetic energy (as this is the one that changes at the starting point) is E = 1/2M * V^2. E is the ammount of kinetic energy, M is the mass, and V is the velocity. As V is constant (the shooting machine will take care of this) the ammount of energy changes. This while two identical kicks from a football player will have the same amount of energy, we can name X here. The lighter ball will have more velocity, the formula for this is a form of the formula above: V^2 = E/(1/2M). This shows us that when the mass decreases, velocity increases. When the different in masses is big enough this will be a significant factor. I'm curious how much this influenced the result