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Homework Help: Finding horizontal force using mass and static friction?

  1. Dec 15, 2014 #1
    1. The problem statement, all variables and given/known data
    There is a box that has a mass of 30 kg. The coefficient of the static friction is 0.75. Find the horizontal force.

    2. Relevant equations
    3. The attempt at a solution
    Fs=(.75)(.98)(.30)=.2205 N

    That is probably way off... I am very confused right now. Could someone please explain the steps to solving it?
  2. jcsd
  3. Dec 15, 2014 #2
    This can't possibly be the exact problem statement. Please provide the exact problem statement (word for word).

  4. Dec 15, 2014 #3
    The mass of the garbage can is 30 kg. The coefficient of the static friction between the can and the ground is .75.
    What is the horizontal force necessary to get the can moving?
  5. Dec 15, 2014 #4
    Much better. Now in your post #1, what does the 0.98 represent, and what does the 0.30 represent (including their units)?

  6. Dec 15, 2014 #5
    .98 m/s/s represents gravity and sorry I typed it wrong. It should be 30 N
  7. Dec 15, 2014 #6
    30 kg not 30 N
  8. Dec 15, 2014 #7
    It should be 9.8 m/s/s. How did the 30 kg become 0.30?

  9. Dec 16, 2014 #8
    Wow yes 9.8 for Gravity. How should I continue then?
  10. Dec 16, 2014 #9
    According to your understanding, you tell me. You almost had it right to start with.

  11. Dec 16, 2014 #10
    Should I multiply (9.8)(30)(.75)?
  12. Dec 16, 2014 #11
    If you're not sure about this, you need to go back and review your text and/or notes. The objective of studying a course is so that you can understand the fundamentals (and use this to solve a wide array of problems), rather than just to solve one specific problem.

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