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Re: Banked road



But in dealing with banked roads they are suddenly asked to
accept that N=mg/cosA. How can this be explained?
Ludwik Kowalski

Cool; I just subbed for a colleague on Friday and was asked this EXACT
question after class. The answer is that this is a dynamic situation, where
the forces are NOT in equilibrium. Although when we draw the figures
everything looks static; the road MUST be applying an unbalanced
force on the car, pushing along the radius of the circle through which the
car is turning. The road now not only supports the weight of the car; it also
provides an additional push inwards that is required for centripetal
acceleration. So the normal force provided by the road must exceed the
weight of the car.

I bet big trucks REALLY tear up banked curves and ramps given all the damage
they do to regular highway surfaces :^).

I will (yet again within 7 days) be showing printouts from PHYS-L to my
students on Monday. And to think my peers consider these intro courses
as unchallenging :^).

Dan MacIsaac, Assistant Professor of Physics and Astronomy, Northern AZ Univ
danmac@nau.edu http://purcell.phy.nau.edu PHYS-L list owner