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Can someone help me with my homework,please?

  1. May 23, 2009 #1
    I don't know how to solve this force and motion problems so I'm asking you for help...if someone knows how to solve them,I would like some solutions.
    thanks!

    1.a horizontal force of 12N pushes a 0.50 kg book against a vertical wall.the book is initially at rest.if coefficient of static friction is 0.6 and of kinetic friction is 0.8 what is the acceleration of the book?

    2.a horizontal force of 5N pushes a 0.50kg block against a vertical wall.the block is initially at rest.if coefficient of static friction is 0.6 and of kinetic friction is 0.8 what is the acceleration of the block?

    3.a 12kg crate rests on a horizontal surface and a boy pulls on it with a force that is 30° below the horizontal.if the coefficient of static friction is 0.40,the minimum magnitude force he needs to start the crate moving is?

    4.a crate resting on arough horizontal floor is to be moved horizontally.the coefficient of static friction is 0.40.to start the crate moving with the weakest possible applied force,in what direction should the force be applied?

    5.a 40N crate rests on a rough horizontal floor.a 12N horizontal force is the applied to it.if the coefficient of static friction is 0.5 and of kinetic is 0.4,the magnitude of the frictional force on the crate is?

    6.a block slides down a frictionless plane that makes an angle of 30° with the horizontal.the acceleration of the block is?

    7.a 25N crate slides down a frictionless incline that is 25° above the horizontal.the magnitude of the normal force of the incline on the crate is?

    8.a 25N crate is held at rest on a frictionless incline by a force that is parallel to the incline.if the incline is 25° above the horizontal what is the magnitude of the applied force?

    9.a 25N crate is held at rest on a frictionless incline by a force that is parallel to the incline.if the incline is 25° above the horizontal what is the magnitude of the normal force of the incline on the crate?

    10.a 32N force,parallel to the incline is required to push a certain crate at constant velocity up a frictionless incline that is 30° above the horizontal.what is the mass of the crate?
     
  2. jcsd
  3. May 23, 2009 #2

    danago

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    Gold Member

    Nobody is going to do your homework for you. They will assist you, but only once you have shown that you have made an effort.
     
  4. May 24, 2009 #3
    you don't have to solve the problems then but can you just give me the formulae?
    and I will see what I can do.
    thanks a lot.
     
  5. May 24, 2009 #4
    Hello tinab16 and welcome to PF!

    In future, I suggest you break this down and start with one question at a time when asking for help :smile:

    Having said that, something that may help you would be to draw a diagram of the problem.

    An equation you may find useful is

    [tex]f_k=\mu_kF_N[/tex]

    Hope that helps. :wink:
     
  6. May 24, 2009 #5
    lol the idea is to HELP you get the solution, not GIVE you the solution. Lets start with newton's laws. The first question mentions force, mass, acceleration, friction... does that ring any bells!?
     
  7. May 24, 2009 #6

    OK.I'll see what I can do with it.
    tnx.
     
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