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!

Block and friction

  1. Oct 3, 2008 #1
    I need help with this question:

    Please see attachement. I tried to solve by making a free body diagram of all the blocks but i don't seem to get to a solution

    Any sugestions on how to solve are greatly appreciated.

    Thanks
     

    Attached Files:

  2. jcsd
  3. Oct 4, 2008 #2

    Hootenanny

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Welcome to Physics Forums,

    Firstly, I'm assuming that since no 'stiffness parameter' given, the question means that the string does not undergoe any compression or extension, would that be correct?
     
  4. Oct 4, 2008 #3
    That is correct, the string compression or extension is neglected. We don't know the material of the string either so we assume the string only applies tension.

    Any idea on how to solve this question. Thank you?
     
  5. Oct 4, 2008 #4

    Hootenanny

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Start by analysing the forces on each block.
     
  6. Oct 4, 2008 #5
    I tried to do the free body diagram for all blocks but I'm confused about the part that says "the blocks do not move relative to each other". Does this mean that the system is moving with constant velocity? and how do you calculate the normal force between block 3 and block 2?

    Thanks for the suggestions
     
  7. Oct 4, 2008 #6

    Doc Al

    User Avatar

    Staff: Mentor

    No, it means that all three blocks move with the same velocity.
    Start by analyzing the forces on each block. If you don't know a given force, label it and continue. (For example, call the normal force N.) Apply Newton's 2nd law.

    Hint: Do the blocks accelerate?
     
  8. Oct 4, 2008 #7
    Thank you Doc Al. Since there is a force applied to m3 there is acceleration, but inside the system the three blocks are stationary.
    I am still not sure how to calculate the normal force. Do i have to consider a contact force between blocks 2 and 3? I am having difficulties picturing this.

    Please help
     
  9. Oct 4, 2008 #8

    Doc Al

    User Avatar

    Staff: Mentor

    Absolutely. That contact force has both a normal and a vertical component.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Block and friction
  1. Friction and blocks (Replies: 5)

  2. Block with friction (Replies: 0)

  3. Block Friction (Replies: 5)

  4. Friction on a block (Replies: 10)

  5. Blocks and Friction (Replies: 3)

Loading...