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!

Incline problem

  1. Feb 4, 2007 #1
    1. The problem statement, all variables and given/known data

    Two objects are connected by a light string that passes over a frictionless pulley, as in Figure P5.26. The incline is frictionless, m1 = 2.00 kg, m2 = 6.00 kg, and = 50.0°.

    (?) Find the speed of each object 2.00 s after being released from rest.

    2. Relevant equations

    I already found the acceleration to be 3.18 m/s2 using the equation:
    a=(m2)(g)(sin50.0)-(m1)(g) / m1 + m2

    I already found the tension in the string to be 25.9 using the equation:
    T=(m1)(m2)(g)(sin50.0+1) / (m1+m2)

    3. The attempt at a solution

    I cannot figure out how to find the speed. I'm not even sure what equation to use for this type of problem. I was thinking S=mass/acceleration. But that equation doesn't take into account the friction.
  2. jcsd
  3. Feb 4, 2007 #2


    User Avatar
    Homework Helper

    "But that equation doesn't take into account the friction."

    It's a frictionless pulley and a frictionless incline, so you don't need to worry about this.

    Since the acceleration is constant, you can just use basic kinematics to get the speed. They've given you the time interval, and you know the masses were released from rest. Just find an equation that links those things.
  4. Feb 5, 2007 #3
    I'm so lost as to how to relate all those things. Do you know of an example...??
  5. Feb 5, 2007 #4


    User Avatar
    Homework Helper

    Don't think of it as a mass-pulley problem anymore. Just think of it as:

    A block initially at rest undergoes a constant acceleration of 3.18 m/s^2 for 2 seconds, what is the speed at this time?

    Think of your basic kinematic equations. What's the definition of acceleration for linear motion?
  6. Feb 5, 2007 #5
    So the equation looks like:
    V=Vo + at
    So, for this problem I know what the a is 3.18 m/s^2 . The t is 2 seconds and Vo is equal to zero. So substituting those factors in, V should equal 6.36 seconds correct?
  7. Feb 5, 2007 #6


    User Avatar
    Homework Helper

    If you mean 6.36 meters/second, then assuming you found "a" correctly (which I think you did), your speed is right.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Incline problem
  1. Incline problem (Replies: 10)

  2. Incline problem (Replies: 6)

  3. Incline problem (Replies: 3)

  4. Incline Problem (Replies: 1)

  5. Incline Problem (Replies: 4)