The reason the newspaper is blurred out is because logo's and businesses
appeared in those ads.
Comments:
But title is misleading - I don't think the weight of the paper only does the
trick... Notice how he flattens the paper down. It's so the air can't get under
the paper fast enough when you hit the ruler . This vacuum keeps the ruler from
lifting the paper, so it snaps f.ex: If you try lifting a sheet of plywood that
is flat on a slick surface, you'll notice how the vacuum created doesn't let you
do it quickly..
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The paper has atmospheric pressure of 32 lbs per square inch or so on it
depending if the guy is at sea level and the weather that day. The ruler breaks
because there is not enough time for the air to flow off to the sides and the
paper is not permeable enough for the air to flow through it.
So in effect the guy might as well have a 32 lb weight sitting on the ruler when
he did this "trick." If he hit the ruler fast enough with the side of his hand,
it will break even without the paper there.
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is called atmospheric pressure, the weight (equal to the air column over the
newpaper) of air is pushing the paper. The bigger the paper you take the better
it will work. (one more thing as you can see he puts the rulers only few inches
out ofthe table, to make sure the momentum created by the impact of arm is lower
than the air pressure). Friction
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everything, including air, has a mass. With the newspaper in place, alot of air
has to be moved quickly, and the rules breaks under the pressure
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when you lay a piece of paper on top of the ruler then the surface area that the
air is resting on is much greater than it was when it was resting on the ruler
alone. So with all of the air pressure on the newspaper, the ruler is unable to
move when quick force is applied to it, causing the ruler to break.
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Sure air tries to equalize when there are two different pressures, but you’re
trying to make this into a chicken/egg argument when its not. The pressure above
(room) is a constant. The force (operators hand) changes the pressure below the
paper (creating vacuum). The ruler/paper/table form a vacuum pump. The break is
due to the force of the hand against drag of the air drawing into the vacuum
pump.
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There's a lot of air above the newspaper, and it weighs a surprisingly large
amount. It takes a lot of force to put that much air into motion, and a fast hit
on the ruler doesn't last long enough for it to move.
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the dominant force at work here is more atmospheric pressure pressing down than
inertia of the paper (it is a fairly thin paper). it's like how it takes a lot
of effort to pull apart 2 microscope slides if you have water in between them.
thats why flattening down the paper is an important part of this trick
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this has nothing to do with air! it is force applied over surface area under the
news paper. and we dont even know if he managed to put glue under neath paper.
also does anybody notice how old the ruler is now-a days rulers are made with
different material. that ruler could of been frozen. yes, I teach the laws of
physics at local College
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Gravity is the key factor in this age old example of resistance. Without its
presence pushing downwards (not pulling, as it's been incorrectly thought for
centuries) on the the molecular air mass (atmosphere), the paper, and then the
ruler, the resulting break could not occur.
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