1. Not finding help here? Sign up for a free 30min 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!

Help with Physics 11 Kinematics.

  1. Feb 12, 2012 #1
    1. The problem statement, all variables and given/known data

    A 5.0kg concrete block accelerates down a 34° slope at 4.2m/s^2. Find the coefficient of friction between the block and the slope.


    2. Relevant equations

    Fg=5*9.8=45

    x=45sin30

    y=45cos30


    3. The attempt at a solution

    a=(mgsinθ-Ff)/m → Ff=mgsinθ-ma

    Thanks
     
  2. jcsd
  3. Feb 13, 2012 #2
    Welcome to PF,
    Have you drawn your free body diagram? How did you get your x and y components? The question states that the slope is at a 34° angle to the horizontal, not 30°.

    Hint: Friction force = μN

    Hint 2: Remember to add units to EVERYTHING.
     
  4. Feb 13, 2012 #3
    Yes, I have drawn a FBD with x and y components that is perpendicular to the ramp.

    I used the Fg to find the x by going Fgsin30°. Which would be the same as Fn.

    Where would I go from this step?
     
  5. Feb 14, 2012 #4
    Why are you using 30° as your angle when it states in the question that it is 34°?

    Your x component isn't the same as your y component, which would be the normal force (Fn). You must also consider the acceleration of the concrete block in your calculations.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Help with Physics 11 Kinematics.
  1. Physics 11 help ? (Replies: 6)

Loading...