What is Needle: Definition and 65 Discussions

A sewing needle, used for hand-sewing, is a long slender tool with a pointed tip at one end and a hole (or eye) at the other. The earliest needles were made of bone or wood; modern needles are manufactured from high carbon steel wire and are nickel- or 18K gold-plated for corrosion resistance. High quality embroidery needles are plated with two-thirds platinum and one-third titanium alloy. Traditionally, needles have been kept in needle books or needlecases which have become objects of adornment. Sewing needles may also be kept in an étui, a small box that held needles and other items such as scissors, pencils and tweezers.

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  1. L

    Determine the medicine's flow speed through the needle

    A hypodermic syringe contains a medicine with the density of water (see figure below). The barrel of the syringe has a cross-sectional area of 2.20 10-5 m2. In the absence of a force on the plunger, the pressure everywhere is 1.00 atm. A force of magnitude 1.80 N is exerted on the plunger...
  2. ~christina~

    Needle and pressure (Bernoulli's equation?)

    [SOLVED] Needle and pressure (Bernoulli's equation?) Homework Statement A hypodermic syringe contains medicine having the density of water. Barrel has cross sectional area A= 2.50x10^-5 m^2 and the needle has a cross sectional area a= 1.00x10^-8 m^2. IN the absence of a force on the plunger...
  3. P

    Calculating Force Needed to Push Fluid into a Vein at 18 mm Hg Pressure

    What force on the plunger would be needed to push fluid into a vein where the gauge pressure is 18 mm Hg? Answer for the instant just before the fluid starts to move. I know i need the density of mercury (in Meters) and that equals = 13.534e-3 / 100 which is 1.3534e-4 for the density...
  4. R

    In what direction does a compass needle point?

    Homework Statement In what direction does a compass needle point? (More than one answer may be true.) T/F In the direction of the magnetic field lines at the location of the compass. T/F Toward the north magnetic pole if a bar magnet is brought near the compass. T/F Toward the south...
  5. N

    Blood pressure and needle insertion

    OK, so I'm new here and really lost on how to these two problems involving blood pressure and syringe force etc. Any help would be appreciated, and if you could somewhat explain how you solved it that would be great, so I can know how to do this in the future. Homework Statement 1...
  6. M

    Needle on parallel lines, problem

    Hi, I was given a problem by the professor, and I feel like I do not know where to begin. Well, here is the problem: -------- Endless, parallel East-to-West lines are spaced 2 inches apart on the ground, and a needle of length 1 inch is randomly tossed on the ground. Compute the probability...
  7. daniel_i_l

    What is the probability of a needle hitting a line on graph paper?

    In the "buffons needle" riddle you have a paper with horizontal lines in it all 1 unit apart and you drop a needle 1 unit long - you have to calculate the chance that the needle will hit a line. but i remembered the riddle wrong so instead i tried to solve the same question with both horizontal...
  8. Amith2006

    Period of oscillation of dip needle

    1)The time period of a dip needle vibrating in the vertical plane in the magnetic meridian is 3 seconds. When the same magnetic needle is made to vibrate in the horizontal plane, the time period of vibration is 3(2)^(1/2). What is the angle of dip of the place? I think in both the cases, it is...
  9. C

    Magnetic Compass Needle: Remanence & Airgap Effects on AC Performance

    1)does a magnetic compass needle have high remanence or low remanence? 2)in a shell type transformer core required to carry DC in addition to normal AC, what effect does the introduction of an airgap have on AC performance of such transformers.
  10. N

    Buffon's Needle problem (Geo Prob)

    http://www.mste.uiuc.edu/reese/buffon/buffon.html#questions can someone explain problem "A" for me please. this isn't for school or homework but just something that i don't understand and would like to know where I'm going wrong. how would i go about solving question "A"? thanks
  11. M

    Facing My Phobia: Overcoming Needle Fear

    Like personally I have a needle phobia. That's for sure. No idea of the real phobia name. I also have like a sort of good reason why. When I was young I had a very bad asthma attack, i was hospitalized, when i was there. They needed to needle something to get my asthma attack under control. I...
  12. E

    Dynamics of a free hanging 3D needle

    Hi! I would be extremely grateful if anyone could help me figure out this mess... I hadn't touched mechanics for too many years and I guessed i gotten myself a little confused... I am trying to model a 3D needle/object in a virtual world... I have done the part on freebodies collision... but...
  13. D

    Overcoming Fear of Needles: The Painless Needle

    Now that HIVs is more rampant across North America, and that there are plenty of careless drug users out there with needles, nothing freaks me out more than a syringe. In fact, I stepped on one once (don't worry, didn't penetrate). It still freaked me out. Now, people are using needles as...
  14. Monique

    HIV needle stick infection rate

    A friend of my mother is a caretaker and accidentially stuck herself in the finger with a needle used on an HIV patient. It probably won't be until 6 mo from now until it can be diagnosed whether an infection has taken place. I was wondering, what are the chances that HIV is contracted and is...
  15. F

    Designing an Electron Source with a Needle Sprayer

    I have seen designs of electron sources that use a heated filament to create a cloud of electrons then apply a voltage across them to accelerate them for whatever purpose. Could you replace the filament with a needle spraying the electrons?
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