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Free Body Diagram, Newton's 3rd

  1. Mar 19, 2009 #1
    [SOLVED] Free Body Diagram, Newton's 3rd

    SOLVED




    1. The problem statement, all variables and given/known data

    A 1200 kg car pushes a 2000 kg truck that has a dead battery. When the driver steps on the accelerator, the drive wheels of the car push against the ground with a force of 4700 N.

    (a) What is the magnitude of the force of the car on the truck?
    (b) What is the magnitude of the force of the truck on the car?


    2. Relevant equations


    fs=[tex]\mu[/tex]sn
    F=ma
    Fnetc/mc=FnetT/FT


    3. The attempt at a solution

    I drew this free body diagram, I am not really sure how to set this problem up but I thought this would be a good start.

    Wanted to see how "right" it is.

    nc = normal force of car
    nT = normal force of truck
    fsc = static friction force
    Fc on T = force of car on Truck
    FT on c = force of Truck on car
    mcg = weight of car
    mTg = weight of truck

    http://img27.imageshack.us/img27/8660/fbda88b.jpg [Broken]


    I've done a little dabbling with formulas from there but nothing great. I haven't solved anything so.. maybe I can at least figure out if my drawing is right.
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Mar 19, 2009 #2
    Newton's Third Law of Motion? :wink:
     
  4. Mar 19, 2009 #3
    Solved! Used the materials forum on this site.

    I know people google questions like these a lot, at least I do. You will find a very good lecture on this exact problem at the link I will provide, 16 minutes into Lecture 6.


    http://www.free-ed.net/free-ed/Science/Physics/physicsMIT01_VOD.asp
     
  5. Mar 19, 2009 #4
    But if you know the concept correctly, you can solve pretty much any problem based on that.
     
  6. Mar 19, 2009 #5
    I hope so, I'm trying it out now.

    To tell you the truth I've been studying these ideas for the past 7 hours and I'm becoming quite tired... so I don't know how well I can apply them at the moment. Normally I am at work right now but I called out to spend the whole night on this.
     
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