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Homework Help: Linear speed of the screw

  1. Apr 25, 2007 #1
    Could somebody help me with this?

    Let’s say I have a screw that is 0.25” dia. I want to screw this screw into the wall.
    First question: If I turn this screw 2 times around its axis, how far the screw will go into the wall?
    Second question: If I rotate the screw at 10 RPM what is its linear speed?
    Please help me with question!!! I can’t figure it out.:cry:

    Let’s pretend that the wall doesn’t resists to the screw at all to go in. I just basically want to know the relationship between linear and rotational speed, when linear speed is parallel to the rotation axis.
    Last edited: Apr 25, 2007
  2. jcsd
  3. Apr 25, 2007 #2


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    Welcome to PF, Shurioz. The questions that you're asking depend upon one factor that you didn't mention: the pitch of the screw; that is, how many threads per inch.
  4. Apr 25, 2007 #3
    It’s a good question. Let’s say the pitch is 20. 20 threads per inch.
  5. Apr 25, 2007 #4


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    You can model the screw as "an inclined plane wrapped around a cylinder".
  6. Apr 25, 2007 #5
    By using the screw example I just wanted to know if the liner speed perpendicular to the rotation axis is the same as linear speed parallel to the rotational axis.
  7. Apr 25, 2007 #6
    Another question about screw threads.

    Let’s say we have a nut with custom threads: 2.0” pitch diameter and pitch-10.
    If I rotate this nut by 55 degrees on the bolt, what would be the traveling distance of the nut?
    Please help!!!
  8. Apr 25, 2007 #7


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    If there are 10 threads per inch then rotating the bolt 360 degrees will advance it one thread or 1/10 inch. Clear now?
  9. Apr 26, 2007 #8
    2 Dick
    Thanks a lot
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