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Homework Help: Friction and Banked road question

  1. Oct 31, 2008 #1
    Hello Everybody. I am having a very difficult time with these two questions.

    The first question:

    The system shown in Figure 4.54 has an acceleration of magnitude 1.77 m/s2, where m1 = 3.90 kg and m2 = 9.40 kg. Assume that the coefficient of kinetic friction between block and incline is the same for both inclines.

    Figure 4.54

    a)Find the coefficient of kinetic friction.?

    b)Find the tension in the string. (N)

    The Second Question:

    A car rounds a banked curve as in the figure below. The radius of curvature of the road is R, the banking angle is θ, and the coefficient of static friction is μs.


    a)Determine the range of speeds the car can have without slipping up or down the banked surface. (Use theta for θ, mu for μs, R and g as necessary.)

    vmin =


    b)Find the minimum value for μs such that the minimum speed is zero. (Use theta for θ, and R and g as necessary.)

    μs =

    c)What is the range of speeds possible if R = 100 m, θ = 10.0°, and μs = 0.110 (slippery conditions)?

    vmin =



    I would really appreciate it if someone could help me.
    Thanks in Advance....
  2. jcsd
  3. Nov 1, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF!

    Hi msq126! Welcome to PF! :smile:

    Hint: try good ol' Newton's second law for both questions. :wink:

    Anyway, show us what you've tried, and where you're stuck, and then we'll know how to help. :smile:
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