1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Hilly road

  1. Sep 30, 2007 #1
    1. The problem statement, all variables and given/known data
    A car with a mass of 1190 kg is traveling in a mountainous area with a constant speed of 78.2 km/h. The road is horizontal and flat at point A, horizontal and curved at points B and C. The radii of curvatures at B and C are: rB = 155 m and rC = 120 m.

    Calculate the normal force exerted by the road on the car at point B.

    2. Relevant equations
    x = f = mv^2/r
    y = -mg + n = 0

    3. The attempt at a solution
    If n = mg then where does the radius come into play? I must have something set up wrong in the forces but I don't know what.
  2. jcsd
  3. Sep 30, 2007 #2


    User Avatar
    Homework Helper

    I think the curves are supposed to be the tops of hills right?

    So N - mg = mv^2/r (during a valley because the center of curvature is towards the top)

    mg - N = mv^2/r (during a hill because the center of curvature is towards the bottom)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook