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Re: Banked road



On Sun, 4 Nov 2001, Ludwik Kowalski wrote:

The normal force with which an inclined plane is acting on an
object is N= m*g*cosA, where A is the angle of inclination.
Students use this approach to calculate accelerations (with or
without friction) or to solve equilibrium problems.

This is not what I find. I generally find that either

a) students improperly use N = mg in all situations

or

b) students properly use both components of the second law
thereby eliminating the need for ad hoc assumptions about the
relationship of the normal force to the gravitational force.

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

I find that students in both categories are generally unfazed by
this. Those in category a continue to use N = mg and those in
category b continue to do the right thing.

John Mallinckrodt mailto:ajm@csupomona.edu
Cal Poly Pomona http://www.csupomona.edu/~ajm