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stateofdogma
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Homework Statement
A Truck is going around a circular track of radius 72m and is banked at 60 deg. A spider is at rest on the side of the truck and the coeffiecient of friction is 0.91, what is the maximum velocity of the truck so that the spider is at rest.
Homework Equations
[tex]F = \frac{mv^2}{r}[/tex]
The Attempt at a Solution
What I did is take the coordinate axes along the wall of the spider, then made -mgsin(%)+ N = -mv^2/2cos(%) for the vertical axes (where (%)is 60 deg ). -mgcos%+ musN = mv^2/2sin% for the horizontal axis. then substitute in N for the horizontal equation and solve for v. (The solution was (mv^2/r)sin60 - mus((mv^2/r)cos60 + mgsin60) = mgcos60, v = 47 m/s When I look at the solution I see that for the vertical axis the centripetal force and gravitational force have the same sign when it equal to Normal force which implies that when you subtract it to from both sides, the normal force is in the same direction as the centripetal force. Isn't the centripetal force just another way of writing the resultant force and should therefore be a result of other forces, instead of contributing itself.
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