Kyle over at Pit of Babel does a delightful job of showing that the textbook propogated myth that two objects dropped from a tower will land at the same time is incorrect. This is pretty evident to anyone who considers a parachute. But, not just anyone can go on to calculate the degree to which this is incorrect with simple, easily understood formulas that call for little more than high school level math and physics, that illustrate which variables are important, one of which happens to be the mass of the falling object. He can.
As the name of his blog indicates, he has a thing about towers, so I suppose it isn't surprising that he has a lot of insight into things falling off them.
Go read it.