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: Inclined place friction problem

  1. Jun 5, 2012 #1
    1. The problem statement, all variables and given/known data

    Body A in Fig. 6-33 weighs 96 N, and body B weighs 88 N. The coefficients of friction between A and the incline are μs = 0.54 and μk = 0.24. Angle θ is 42°. Let the positive direction of an x axis be down the slope. What is the acceleration of A if A is initially (a) at rest, (b) moving up the incline, and (c) moving down the incline

    2. Relevant equations


    3. The attempt at a solution
    I am so confused on this problem i dot even know where to start but I know part a is 0!
  2. jcsd
  3. Jun 5, 2012 #2
    Here is the diagram

    Attached Files:

  4. Jun 5, 2012 #3
    Let's start with by drawing a free-body diagram for each mass.
    Mass A has a force downward to center of earth equal to its weight, the string that pulls it and third the friction that will appose the motion of the mass.
    Mass B has 2 forces acting on it. Its weight and the string that pull up.

    Remember if there is the net forces(ƩF≠0) on each mass then there's acceleration as in Newton's First Law.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook