Needle Definition and 62 Threads

A compass needle can be magnetized to point to the north. Am I correct in thinking that the needle could have been magnetized to point to any other horizontal direction?

This is much like the "grain of sand" at near speed of light hiting Earth, but now targeting Jupiter with a needle! What if... Any way, which is the correct way to analyze this kind of scenarios? For example, I think than being the speed of the needle near c, is nonsense to think about the...

Let's say we are pushing water down a needle, the contact angle between the needle and the water is ##\mathrm{45°}##. For simplicity let's assume there is no gravity. As the water is initially moving down in the left image, the angle ##\theta=\mathrm{45°}## and the surface of the water is a...

So this is a sketch I made of the situation and this is my approach my approach is incorrect , and Idon't seem to find the mistake , maybe B*p isn't correct. Any ideas?

My guess is (c) since the rest of the options do not make sense to me but I am not sure about the shape of the graph. Is (c) the correct answer? If yes, how to know whether the shape will be like in the option (straight line then curve downwards) or other shape like straight line only (like y =...

Hello all friends, My questions about the these two types of bearings. I know that what is purpose of usage. But I don't know where can I use them. If someone knows information about that, please inform me. Thanks you all.

I think Voltmeter's needle will not jump in both situations. But the answer is yes. I am going to use this to explain why. The reasons to create the voltage are by - The changing by time of Magnetic field - The move of the object in magnetic field In both situations, they are not occur so I...

My approach to this problem is a little laborious, it involves three coordinates, probably it is right, but tiring and extensive beyond what the question wanted. Be the origin in the rectangle middle. It would be like: imagine a rectangle with opposite sides L and R with length l, so to find...

Buffon's needle was presented as a problem in David Griffiths' "Introduction to Quantum Mechanics". In the book, a needle is of length l is dropped randomly on a sheet of ruled paper with the lines of the paper also a distance l apart. It is required to find the probability of the needle...

So I'm reviewing old lectures to prepare for an exam soon. This is about polarization. E fields, D Fields, etc. My professor labeled this diagram like so. The figures my professor drew are cavities in a dielectric if you can't read her handwriting. However, I can't seem to figure out why the...

I attempted the question but it was wrong... I don't understand where i went wrong my working seems logical, can someone please help. When a needle is gently placed on the surface of still water (γ = 0.0730 N.m-1) it can be supported by surface tension if the mass of the needle is small enough...

Homework Statement It is known that when rubbing a needle on a magnet, the needle will become magnetized. If you rub the needle on the north side of the magnet, will it point differently than if you rubbed it on the south side of the magnet? Does it matter what direction you rub the needle...

Hi, I am have been trying to figure out the correct way to mount a needle bearing. I have previously worked with ball bearings. Here is the application: The needle bearing will be pivot point of a swing arm of a trike. Another will form the central pivot point that breaks the vehicle from...

Buffon's Needle A floor is ruled with equally spaced parallel lines a distance D apart. A needle of length L is dropped at random on the floor. It is assumed that L no more than D. What is the probability that the needle will intersect one of the lines? This problem is known as Buffon’s needle...

this is a small part of a problem on tidal forces and I wasn't sure what the question asks as it seems to me that more information is needed. Am I right or is there something I am missing? the question goes as: "A spacecraft approaches a neutron star of radius 10 km and mass 1.5 times mass...

Hello , I'm trying to model the forces on a needle being inserted in a tissue. Needle tip penetrates the tissue surface and as it moves through the tissue, it experiences friction from needle-tissue interaction. Friction arises from the pressure exerted by surrounding tissue as it grips the...

Hello, How to perform and know north south from magnetic needle compass?? as in this picture it show North + south = south + north so, how to find Earth direction??

http://i66.tinypic.com/2yts08m.jpg I was doing an experiment in which i have a needle perpendicular to a metal plate. I run 210kV between them. I want to find out the electric field between the two, and I also want to know the electric al field density throught the metal plate? Pls help. I...

If a compass is placed above a current carrying wire, why does the compass needle align itself in the direction of the magnetic field produced by the wire?

hi, i know this question is a bit unnecessary but i just want to know if i got my concept right so, here's the question if you have a compass pointing northwards placed between two parallel wires carrying opposite current, does the needle deflect? my answer is the needle won't deflect since the...

A hypodermic syringe contains a medicine with the density of water (figure below). The barrel of the syringe has a cross-sectional area of 2.18 10-5 m2. In the absence of a force on the plunger, the pressure everywhere is 1.00 atm. A force of magnitude 1.78 N is exerted on the plunger, making...

Buffon`s needle problem described the probability of crossing a set of parallel lines with a known distance between them by a needle of a known length. What is the probability of crossing a circumference of a circle with a known radius by a needle of a known length? I feel that a simple answer...

http://www.colorado.edu/physics/phys3320/phys3320_sp12/AJPPapers/AJP_E&MPapers_030612/Griffiths_ConductingNeedle.pdf I was reading this paper, and was confused by a result in section 2-A. (Heck they even mention they weren't expecting it themselves). The purpose of the paper is to find the...

So I read that if you put grease on a needle it will float on water . Why does this happen?

Homework Statement Eric looks at his compass to check the direction to north. At a point two (2.0) meters below Eric, a cable is drawn from south to north and the current running through the cable is 50 Amperes. This current makes the compass needle turn wrong. How big is the angle deviation if...

Homework Statement You place a magnetic compass on a horizontal surface, allow the needle to settle, and then give the compass a gentle wiggle to cause the needle to oscillate about its equilibrium position. The oscillation frequency is 0.321 Hz. Earth's magnetic field at the location of the...

Homework Statement I'm an introductory electromagnetism course and in lab we were observing how an electric current could deflect a compass needle. however, i also noticed that the batter itself (with no wire attached, so no current) could also deflect the needle. (for ex, if you brought the...

I am trying to size a needle valve to make sure that it can allow the required flow rate at the fully open position (0.025 m^3/s). For a given Cv you should be able to calculate the maximum flow rate through the needle valve provided that you know the temperature of the gas and the pressure drop...

In all the literature that I have seen it is mentioned that these two are "branches" of integral geometry, but no where I can see the exact connection since one is connected with probability and the other is an integral. I have seen this, but it is not clear...

A compass is placed near a solenoid. It is closer to the North pole generated by the coil. The magnetic north is 90 deg relative to the compass and the solenoid. The strength of the solenoid is equal to the strength of the magnetic north. In which direction will the compass needle point?

A needle on a broken car speedometer is free to swing and bounces perfectly off the pins at either end, so if you give it a flick it is equally likely to come at rest at any angle between 0 and pi. If the needle has a length r, what's the probability density ρ(x) of the x-coordinate of the...

What will happen If I place a magnetic needle inside a solenoid, I mean will the South Pole of the needle be directed towards the South Pole of the solenoid since it is north from inside and the same way regarding the North Pole

Awhile back I had been messing around with batteries, copper wiring, compasses and small neodymium magnets; during this time I figured out how to flip the polarity of a compass needle. The most reliable way was to hold the two magnets above the compass needle and force, as best I could, the two...

Homework Statement 1)How do we obtain the formula of torsional rigidity ,c=∏nr^4/(2L) ?From experiment? then how do the ∏ come from? How do they know the n here is the rigidity modulus? Why it is not the young's modulus? 2)Is Maxwell needle method same as the torsional pendulum? Both can be...

[b]1. Homework Statement [ How do I get I1( the moment of inertia of the picture b) ?is just a math problem but really no idea. Homework Equations I=mr^2 The Attempt at a Solution maybe centre of mass . Guide will do . please help , thank

Homework Statement Physicians perform needle biopsies to sample tissue from internal organs. A spring-loaded gun shoots a hollow needle into the tissue; extracting the needle brings out the tissue core. A particular device uses 8.4 needles that take 81 to stop in the tissue, which exerts a...

https://www.youtube.com/watch?v=qHrBhgwq__Q&feature=player_detailpage Don Pettit, unfortunately, narrates, but doesn't explain much. The main needle is Teflon and the other needle by the injection of the water droplets (seen near the end of the vid) is Nylon. The site asks about the choice of...

The torque experienced by the compass needle is m X B , m being the magnetic moment of the compass/magnet and B being the Earth's magnetic field. The magnetic moment is along the axis pointing from South to North and the magnetic field will depend on where the compass is on the surface of the...

I have a question about https://www.amazon.com/dp/B002RS5IKA/?tag=pfamazon01-20 product. It is an autosampler shell vial with a polyethylene plug style needle closure. Does anyone know whether the plug on this vial will be resealable? In other words, will it be able to withstand multiple...

What would be a typical value of the magnetic moment of a compass needle (in SI units)? Thanks :-)

Homework Statement A small compass needle is situated in a uniform magnetic field. When displaced from its stable equilibrium position through a small angle and then released, it oscillates with a frequency of 5 Hz. A millijoule of work is needed to twist the compass needle round through...

Homework Statement A patient is to be given a blood transfusion. The blood is to flow through a tube from a raised bottle to a needle inserted in the vein. The inside diameter of the 3.82 cm long needle is 0.393 mm and the required flow rate is 3.88 cm3 of blood per minute. How high should...

Homework Statement A compass needle points 19.1 degrees E of N outdoors. However, when it is placed 9.80 cm to the east of a vertical wire inside a building, it points 55.7 degrees E of N. What is the magnitude of the current in the wire? The Earth's field there is 4.80×10-5 T and is...

Why does one "dips" down and the other rotates?

Homework Statement A patient is to be given a blood transfusion. If the inside diameter of the 4.0 cm long needle is 0.40 mm, the blood pressure in the arm is 2400 Pa, and the required flow is 4.0 cm³/min, how high h should the bottle be placed? (ρ = 1050 kg/m³, η =0.0040 Pa·s)...

I am a little confused by movement. It is difficult to explain, but here goes. Say I have a needle which is almost touching a pane of glass, so close if fact that the smallest movement toward the pane would result in the needle touching it. My confusion is, if the needle has to move to touch the...

Homework Statement A radioactive needle contains 222 Rn (t1/2=3.83 d) in secular equilibrium with 226 Ra(t1/2=1600 a). How long does is it required for 222 Rn to decay to half of its original activity?Homework Equations A(t) = -\frac{dN(t)}{dt} = \lambda N(t) The Attempt at a Solution...

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...

[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...

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...