Static Definition and 1000 Threads

Hello all. I am currently studying electromagnetism with Griffiths' books, and I have already donde electrostatic and magnetostatics. Now I am reviewing Ohm's law en emf concepts, but I have a doubt: In griffths book, when explaining ohm's law and emf, it seems to me that he assumes...

I am doing a research project about wind pressure and the different uses one can achieve by changing the pressure, volume and speed. I am comparing a hot air balloon ride vs an air plane vs human flight. I am looking and what minimum and maximum MPH is needed to achieve human flight and with...

I am confused with the wording for a static friction problem; this particular wording also lead me to a conceptual question on the force of static friction. It all started with a question in my textbook that I figured out how to solve for the right answer. The question states, a box of m is...

Homework Statement If i have a block that is d distance back from a slope, and I have cable coming out of the block (lets assume at ground level) that goes over to a fulcrum at the ledge of an incline of angle theta down to a block of mass m. What is the downward force at the fulcrum point...

i am having some trouble figuring this out I can not figure out which formula to use i have tried Mass x G x Static Friction which resulted in 1 x 2 x 9.8 = 19.6

Hi, I'm hoping I'm in the right section, I wasn't quite sure. For a couple of days I've been trying with no success to make a crystal radio. To save me the trouble of having to build my own components, I decided to build a tuned circuit that should resonate at a radio frequency (and insert...

Hello, I hope someone can help me with this question. "Design a simple experiment that you could carry out in your home to i) determine the coefficient of static friction between an object and a surface. ii) prove that the coefficient of static friction is dependent only on the surfaces in...

Static spacetimes can be defined as having no g_{tx} component of the metric. Alternatively we can say that they are foliated by a bunch of spacelike hypersurfaces to which the Killing vector field \frac{\partial}{\partial t} is orthogonal. How are these two statements consistent...

I am using a negative ion generator module that I purchased to generate a static electric charge in a 4' x 7' aluminized mylar blanket. I made a cage out of 3/4" PVC tubing to hang the mylar from (vertically) - I want to suspend the mylar from the PVC so that the mylar is insulated from any...

Hi, I understand the definition of stationary as existence of a timelike Killing vector field and as a result the fields (metric plus anything else e.g. gauge fields etc) cannot have any time dependence. Static is a stronger constraint that satisfies the above plus requires the Killing vector...

A uniform vertical beam of mass 40 kg is acted on by a horizontal force of 520 N at its top and is held, in the vertical position, by a cable as shown. a) Draw a free-body diagram for the beam, clearly labeling all of the forces acting on it. b)Calculate the tension in the cable...

Homework Statement A 30Kg neon sign is suspended by two cables, as shown. Three neighbourhood cats (5.0 Kg each) find the sign a comfortable place. Calculate the tension in each cable with the cats are in the positions shown. Homework Equations xCM = m1x1 + m2x2 ...

Homework Statement A uniform vertical beam of mass 40kg is acted on by a horizontal force of 520N at its top and is held, in the vertical position, by a cable as shown in the attached picture. a) Calculate the tension in the cable b) Determine the reaction forces acting on the beam by the...

Homework Statement One hundred millilitres of water is poured into a U-tube that has a cross-sectional area of 1 cm2. Then 100 millilitres of oil, with a density 80% that of water, is poured down one side of the U-tube so that the oil floats on the water. Find the difference in height of the...

How do I measure static electricity or is it even possible?

Hi, I haven't done many problems of this nature so there are a few steps in my working that i'd like to check are acceptable/agree with what the question implies. Homework Statement A water tower is a familiar sight in many towns. The purpose of such a tower is to provide storage...

Homework Statement block is placed on a ramp at an angle of 39.4 and height of the ramp is 1.610m and the mass of the block is 8.54kg if coefficient of kinetic friction is 0.111 and the coefficient of static friction is 0.173 what is the speed of the block at the bottom of the ramp. if it...

Homework Statement A diving board 3.00m long is held down at the left end and is supported underneath at a point 1.00m to the right of the hold. A diver weighing 500N stands at the other end. The diving board is of uniform cross section and weighs 280N. Find (a) the force at the support...

In a famous experiment with a balloon and wool. http://phet.colorado.edu/sims/html/balloons-and-static-electricity/latest/balloons-and-static-electricity_en.html Initially the balloon and wool pullover have no ions. I understand how positive ions are formed, that you apply energy to the...

In a recent physics class I took, my teacher explained how friction is not affected by surface area, but by the "bumpiness" of the two objects and the mass, as well as other things, but not the surface area. But this made me wonder how nails get harder to pull out the deeper they are embedded in...

Homework Statement A computer scientist has dropped a tiny pizza crumb onto a magnetic disk. Later, when it's turned on, the disk is rotating at 88 revolutions per second about its axis, which is vertical. The coefficients of kinetic and static friction between pizza crumbs and the disk are...

Homework Statement Rod AB is attached to a collar at A and rests against a roller at C. a = 107mm, l = 642mm, P = 110kN and Q = 30kN, determine: The reaction at A (by the vertical rod) (Unit: kN) The magnitude of the reaction at C (Unit: kN) Homework Equations This is my first...

Ignore the constant speed I have no clue how to do this problem

I have read that static friction does no work and energy of the system is conserved if only this type of friction exists. Is this only an experimental fact, or can it be proved from basic principles? If it can, how?

If I rub my socks around on the carpet, then touch the end of my unplugged laptop charger, and get a spark, why doesn't the breaker pop?

Homework Statement Static friction can never do work on an object. a. True b. False Homework Equations The answer is False, indicating that static friction can do work. The Attempt at a Solution W=fd, when d=0 w=0 regardless of the force. How does this work? Or is the online...

i heard that when we rub a finger on a nonconducting material 20000v gets generated,we don't get electrocuted because of low current.is that true?...really 20k?.. i got a earful when i touched a smd ic from my professor,thats why i had this doubt...so any help please??

Hi, I'm an automotive technician. I have trouble understanding a couple basic electrical concepts. The problem is that I am more or less taught that current flows through CIRCUITs. When analyzing electrical problems, I think current will only flow if there is a voltage (potential...

I just don't know where did the numbers 5,4, and 3 came from. please explain. I'am asked to do this assuming clockwise moments as positive, compute the moment of force F = 200 kg and force P = 165 kg about points A, B, C, and D. the solution picture is here

Homework Statement A box rest on an incline making a 34 angle with the horizontal. It is found that a parallel force to the incline of at least 235 N can prevent the box from sliding down the incline. If the weight of the box is 800 N, find the coefficient of static friction between the...

Homework Statement 4.00-kg block rests on a 30.0° incline as shown in the figure. If the coefficient of static friction between the block and the incline is 0.700, what magnitude horizontal force F must act on the block to start it moving up the incline? Homework Equations F=ma...

The attachment provided shows a frame in which a large fan is to be rested on. The fan is to remain static and has a weight of 6,060 kg and the location of the centre of gravity is shown in the attachment. Each frame member has a cross-section of 200h x 90w. I would like to know HOW to calculate...

A 10kg block is at rest on the floor, and then a force of 30 N pushes on the block horizontally. If the coefficient of static friction between the block and the floor is μs= 0.33 and the coefficient of kinetic friction between the block and the floor is μk= 0.20, what is the acceleration of the...

Homework Statement Two supports, made of the same material and initially of equal length, are 2.0m apart. A stiff board with a length of 4.0m and a mass of 10 kg is placed on the supports, with one support at the left end and the other at the midpoint. A block is placed on the board a...

Homework Statement A car (m = 1680 kg) is parked on a road that rises 17° above the horizontal. What are the magnitudes of (a) the normal force and (b) the static frictional force that the ground exerts on the tires? Homework Equations FsMAX = Mu*FN or in this case: FsMAX =...

1. a 5.0 kg block is pushed up a wall by a 90N force. Assume that the block starts from rest and that it has an acceleration of 0.5m/s^2. a. find the coefficient of kinetic friction between the block and the wall. b. Find the work done by each force acting on the block. c. Find the...

Unfortunately there's no link to the test. This is from the test administered a month ago. Homework Statement A choppah is flying horizontally at constant speed. A perfectly flexible uniform cable is suspended beneath the choppah; air friction on the cable is NOT negligible. Which of...

Homework Statement The problem reads : You are riding your motorcycle one day down a wet street that slopes downward at an angle of 20 ∘ below the horizontal. As you start to ride down the hill, you notice a construction crew has dug a deep hole in the street at the bottom of the hill. A...

Hello, How is it possible to calculate the static thrust from a fan given power, radius, air density, and propellor efficiency? I've did some research and found various equations that all gave me varying results. Does anyone know what the real static thrust equation is? Thanks...

Hi, I would like to clear some doubts over the field of a rotating magnet. I understand that in a typical alternator or generator , brushed or brushless , the current in the wires is induced because the opposite poles of either a permanent or electromagnet pass by the coils and the magnetic...

Please could somebody explain how the coefficient of static friction can be quoted as a constant in tables etc? \mu_s = F_s/ R In most cases the reaction force is constant but as I push the box harder the friction force increases. Is \mu_s actually the coefficient of limiting friction? Or...

MIT has a Physics Demo called "Rubber and Glass Rods with Tinsel and Balloon" (Not sure if I can post links but easily found on youtube). I have watched the video several times but am a bit puzzled. First the lab technician charges the rod by friction but then when he moves it close to the...

"Static" moon question for a book Hi there, I was wondering if some scenario (about the moon) was possible for the book I'm writing (heroic fantasy) : - my planet is a standard one, potentially bigger than earth - I'd like my moon to be always between my planet and the sun, so whenever...

Homework Statement When you rub a gold sphere with rabbit's fur, the gold takes on a negative charge (and the rabbit fur positive). Suppose the gold sphere has a mass of 190.0 g and it obtains a net charge of 0.540 μC. Calculate the ratio of the number of electrons added to the gold sphere to...

I have two reservoirs, connected by two pipes. The first reservoir is higher in elevation than the second. If the system is full of static water, what would the total energy line look like? Since the velocity of the flow through the system is 0, would the total energy line just be a straight...

I was wondering if and/or how one would could calculate the the generation of static electricity between 2 materials. For example material A is immersed in substance B and moves within it at a constant velocity. Knowing the velocity and volume / surface area of material A and the electron...

Is there a simple way to "make" static electricity from an AC outlet? Looking for a way to make my hair stand (what is left of it) on its end for an experiment. Thanks for your comments in advance.

Hello all, I watched a youtube video where you can rub a plastic tube on your hair, and the static electricity generated will pull a stream of water falling from a faucet. My question is, how would this be possible to do electrically? Meaning, using electricity or a battery powered...

Is rolling friction considered static friction? After all, the two surfaces are not moving at the point of contact. My textbook separates static and kinetic friction.

In my textbook, there is a problem that made me think a bit more (this is not what the textbook was asking). In the problem, there is a 1500 kg car traveling at 30 m/s on a 10 degree sloped hill (the car is driving uphill). The driver slams on the brakes and skids to a halt. We have to...