Question:
why do different objects of different weight drop at the
same speed in air.

Replies:
Over short distances, indeed you are right. Sir Isaac Newton found that
the acceleration of an object directly increased as the force on that
object increased. He also found that the acceleration decreased as the
mass increased. In equation form, it looks like:

a = F/m

If you double the mass, you also double the attractive force the object has
toward the earth. The equation looks like:

a = 2F/2m

The 2's cancel, giving the same equation as before:

a = F/m

So you see, the rate at which the falling object increases its speed is
independent of mass!

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