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Doug Miller[_4_]

"hr(bob) " wrote in news:e2255331-85a6-40d8-8f91-
:

If the cannonball is larger, it must be more affected by air
resistance

So you think a cannonball is more affected by air resistance than a BB ???

so something is wrong with your conclusions.

No, something is wrong with your reasoning. The *total* force of air resistance acting on the
larger object is of course greater, but _in proportion to its mass_ it's much smaller.

Now, if the
ratio of diameter to weight is different, then maybe what is
postulated could be true.

You are overlooking the fact that the effect of air resistance is proportional to the surface
area of the object, whereas its momentum is proportional to its mass and thus (if it is of
approximately uniform density) to its volume -- hence the larger the object (assuming
constant density) the *lower* the *proportional* effect of air resistance.

And *of course* the ratio of diameter to mass (not weight) is different.

Consider two solid spheres, one 1 cm in diameter, the other 2 cm in diameter. Since volume
is proportional to the *cube* of the radius, the volume of the second is 8 times that of the first,
and if they are made of the same material, the ratio of their masses is also 8:1, while the
ratio of the diameters is 2:1. I'll leave it to you to calculate the ratio of the surface areas.