Diameter Definition and 508 Threads

I have read that to increase motor magnetism that an increase in the windings increases the number of tiny magnets that can be used to provide the magnetic force. I have also read that increasing the cross section of the rotor increases the efficiency. Finally I have read that increasing the...

I kind of have a stupid question. How much more massive would the Earth have to be for the average person to weigh about 50 more pounds? How much bigger could the Earth's diameter be? Thanks.

Homework Statement A bicycle tire rotates at 30 radians/s. If the bicyclist travels at 10 m/s, what is the diameter of the tire? Homework Equations I found; for angular speed, w=v/r and for linear speed; v=rw where v=m/s and w=radians/s So if i am thinking correctly, i already know my angular...

Hi Friends, I want to know that why one can't achieve diameter of a laser less than the wavelength of the beam in order to get more power through a lens. please explain in simple Physics

I'm designing a testing unit where I need to estimate the smallest diameter of a short complex pipe (around 1 meter, three bends and some diameter viariations). Since the pipe is being cooled down in a water bath after production, my idea is to force water with a known pressure in one end of the...

Homework Statement What is the volume of a tank that is 8 ft in diameter and 15 feet high Homework EquationsThe Attempt at a Solution Π x (4ft) 2 x 20ft 3.14 X 24ft x 15ft = 1130.4

I think I read somewhere that Feynman once said that if we could measure the earth’s diameter, it would be maybe an inch short of what we would expect from the circumference and Euclid. Is that correct? (Did he actually say that?) It seems to me that it would be a tad longer?? I see a clock...

Homework Statement How we can determine The diameter of the lens of the camera approximitly that this picture took with that? ( we know that lens of the camera made by some parts but we count them as a thin one in Practical calculations ) Homework Equations m = q / p 1/f = 1/q + 1/p f =...

Hello guys, I was wondering if you could guess or even calculate the diameter of a camera lens with a picture of a ruler.

Hello, Gravitational length contraction inside Earth means, the measuring rod is also shortened and in consequence inside is more space than according to the mathematical circumference of an empty geoid. I´d like to know something about this discrepance: mathematical diameter - physical...

Homework Statement Convert the diameter to inches or to feet. Inches = 28 feet*12 inches/foot + 4 inches = 340 inches. Feet=28.333 Radius = 170 inches or 14.167 feet. Area of the bottom in square inch = 3.1416*170*170 = 90,746 sq in Area of the bottom in ft2 (square feet) = 3.1416 *...

Homework Statement The center of a 1.00 km diameter spherical pocket of oil is 1.00 km beneath the Earth's surface[/B]. Estimate by what percentage g directly above the pocket of oil would differ from the expected value of g for a uniform Earth? Assume the density of oil is 8.0*102 kg/m3...

The electrical resistance of a wire varies directly with the length of the wire and inversely with the square of the diameter of the wire. If a wire 50 feet long and 2 millimeters in diameter has a resistance of 0.265 ohms, find the length of a wire of the same material whose resistance is 0.068...

Hey guys, I've been having an issue with my approach to this problem. I'm stuck after I get the deformation... : 1. The proportional portion of the tension-strain diagram for an aluminum alloy is shown in the figure (attached). The specimen used for the test gauge length of 2in and a diameter...

Homework Statement Daphne goes to the kitchen for a glass of water. She turns on the faucet so the stream of water is laminar flow. She notes that the diameter of the water steam decreases with distance below the faucet assuming that the water exits the faucet of diameter D with speeds v0...

As an example let's say The diameter is 28' 4" how do you convert into inches and to feet

Hello, I'm having an issue trying to solve an equation- the problem is worded as such: "A tie bar is made of a material having an ultimate tensile strength of 231 mPa, and must carry a load of 255 kN. What is the diameter of the bar if a factor of safety of 7 is required?I know that the...

If I have water being pumped through two lengths of pipe, both at 50 psi, but one pipe is 1.25" diameter and the other is 10" diameter, approimately how many gpm will be flowing through each pipe? Thanks in advance!

Homework Statement My vocabulary is pretty bad in specialized English, so I have to post a picture of problem There are three pipes, the cross-section changes and all measures are illustrative, I need to find an easy formula to find the diameter of d3, so I can create formula in Excel and...

Hey! (Smile) $$T=(V,E) \text{ tree }$$ $$\text{diameter of a tree } = \max_{u,v \in V} \delta(u,v)$$ $$\delta(u,v)=\text{the length of the shortest path from the vertex u to the vertex v}$$ How can we calculate the diameter of a tree,when we are given the algorithm of the Breadth-first-search...

How do you solve a question like this ? :you can obtain a rough estimate of the following simple experiment-let a droplet of oil spread out on a fairly large but smooth water surface .the resulting oil slick that forms On the surface of the water will be approximately one molecule thick. Given...

Homework Statement The figure below shows a snapshot of a standing wave on a composite string. It is a node in the composite point. If the aluminium string has a diameter of 1.50 mm, which diameter does the steel string have ...

Hello guys I want to know how the wheel diameter of car affects the car's performance parameters(physical significance) such as 1)speed 2)torque 3)handling. I would also appreciate if some equations are used to substantiate the physical understanding of these.

Homework Statement 55.847 grams of iron contain NA=6.02E23 atoms. the density is ρ=7.87 [gr/cm3]. What is the diameter of the iron atom Homework Equations The Attempt at a Solution The volume of 55.847 grams is: $$\frac{55.847}{7.87}=7.1[cm^3]$$ I assume the NA number of atoms is...

Hello, My knowledge on fluid mechanics is on a introductory level. When explaining, it would be great if you could explain in simple English and also like teaching to a student who isn't very good at the subject area! I've been reading a lecture slide and have been trying to follow the example...

8) The diameter of a car's tire is 52cm. While the car is being driven, the tire picks up a nail. a) Draw a graph of the height of the nail above the ground in terms of the distance the car has traveled since the tire picked up the nail. For this part, I drew a graph with the max 52, the mid 26...

Hello! ;) I am given this exercise: A graph has as vertices the $64$ squares of an usual chessboard and two squares are connected with an edge if and only if they have a common side.Which is the diameter of the graph? I thought that the diameter is equal to $64$,but I am not sure..Could you...

I am planning to custom build a water tank into which a household washer should discharge it's used water. I have estimated that a tank holding 60 ltrs would be sufficient. This quantity should be released into the building's drainage system within about an hour because the system is old and has...

I read a post here on PF about angular diameter, https://www.physicsforums.com/showthread.php?t=91704 I *THINK* I understand the math, my question is the actual measurement of Jupiter. Is it done at zero magnification (how?!) or 100x or ??x And with what piece of equipment?

Hello. I have 2 large diameter cylindrical shells that are "rabbetted" together. I am trying to determine the approximate load required to pull them apart without much success. The parameters are as follows (all length dimensions in inches) and result in a .005" (diametric) interference...

In showing diam(cl(A)) ≤ diam(A), (cl(A)=closure of A) one method of proof* involves letting x,y be points in cl(A) and saying that for any radius r>0, balls B(x,r) and B(y,r) exist such that the balls intersect with A. But if x,y is in cl(A), isn't there the possibility that x,y are...

Homework Statement Prove that the union of a collection of indexed sets has finite diameter if the intersection of the collection is non-empty, and every set in the collection is bounded by a constant A. The Attempt at a Solution The picture I have is if they all intersect (and assuming...

Hi everyone, I have a problem (which is likely to be fairly simple), which I need a hand to resolve. I'm trying to determine the impact of changing the internal diameter of the hose/fitting system in a compressed air system (in this case a portable compressor, with an inbuilt air receiver)...

I am interested to see if there is a way of creating a metal ring which has a variable diameter, the only way I imagine that this can be done is using segments which come together to form a circle, once pulled away the diameter changes however, the problem I face is that when the segments are...

Tom and Jerry both push on the 3 m diameter merry-go-round shown in the figure attached. (a) If Tom pushes with a force of 40 N and Jerry pushes with a force of 35.2 N, what is the net torque on the merry-go-round? (b) What is the net torque if Jerry reverses the direction by 180 degrees...

Hello. I came to this forum to seek help for this question, since I cannot find it anywhere on the internet, nor even books. I have to calculate a maximum of a radiated wavelength of a neutron star. Sorry I don't know how else could I translate it from to English. All I was given is that it's...

Hi, I'm not an engineer but I do dabble in working out solutions to engineering problems in the manufacturing environment. I am working on a project/idea at present and I need to be able to calculate the height that a single piston and cylinder, internally combusting, can project a 100kg weight...

Homework Statement Two circular disks spaced 0.50 mm apart form a parallel-plate capacitor. Transferring 1.70 ×109 electrons from one disk to the other causes the electric field strength to be 3.50 ×105N/C. What are the diameters of the disks? Homework Equations Refer to attachment...

Homework Statement Helium at 20°C passes through a pipe with an initial diameter of .3 meters decreasing to .25 meters. The helium flows at .30 kg/s and an initial pressure of 200 kpa. Find the difference in pressure ΔP across the decreasing section. Assume incompressible and inviscid flow...

Okay, this might be a stupid question, but I have a sheet with all the formulas to find all kinds of anything you'd need to find about a gear. However I am confused by when it says outside diameter. Is outside diameter the same as circumference? How do I find outside diameter using either the...

Hi Im thinking of constructing a millwheel with flat fins to run in a stream. Is there a formula i can use to calculate the most efficient ∅ to construct it , when taking into account the velocity and area the stream and the surface area of the fins when submerged. and their relevant angles...

Hello guys, first of all excuse me if I make mistakes, but English is not my native language. So, I am creating a 4 speed gearbox, I know the ratios of the gears I will be creating, I know the distance between the primary shaft ( the one coming for the engine`s flywheel ) and the secondary...

How many neutrons are in a neutron star with a diameter of 42.0 km? I was under the impression it was just (42.0e3/1e-15)^3 = 7.0048e58 but that's wrong??

Hello, I am looking for some help in understanding jet diameter growth due to entrainment. I have an impingement plate positioned approximately 20 cm from the nozzle exit. Is there an equation or information that will allow me to figure out how a free jets diameter grows the further it gets...

I have a homework question that I am having troubles with. Q: By equating the pressure at the centre of an icy planetesimal to the maximum pressure that cold ice can sustain without deforming, about 40 MPa, find a lower limit to the diameter of an icy minor planet. The part I don't...

Hi guys, Say we have a balloon, not completely inflated like in the sketch picture below. I would like to come up with a set of equations connecting between the increase in pressure inside the balloon and the change in the following dimensions as a result: 1. "neck" length (shown as 40mm...

Hi everyone, In the attached diagram there are two hydraulic systems. The cylinder areas for each system are the same. The only thing that is different between the two systems is the pipe joining them, system B having a much smaller ID. Pascals law states that these two systems would act...

How do I calculate the diameter of a cyclinder using F= P x A ?? I need to be able to state the diameter of a pneumatic cyclinder using F= P x A I have the following given information; This is a lift with the required force being 2000 Newtons. The pressure applied to the system is...

Here is the link to the question...

Hi guys, I have a question and I would love some guidance or external reference for relevant information. I have a normal compression spring (see attached pic - 1), I apply a force to compress it by x length. I want to create a formula connecting between the small increase of the outer...