Body Definition and 1000 Threads

This is the set up to the question that we got for homework: Pit and Plank. A wooden plank is placed over a pit that is 5.00 m wide. A physics student stands in the middle of the plank and begins to jump up and down such that she jumps upward from the plank two times each second. The plank...

Say we have a +Q charge located inside an isolated spherical conducting body and I want to know the E field at some point P outside the conducting body. I reliase that since this is a conducting body, the E field inside is zero. So by Gauss's Law, ##Q_{enclosed} = 0##. The only way for this...

Homework Statement Draw a free body diagram of each object in Italics, that is in centripetal acceleration, and name the force causing this centripetal acceleration. a. Moon in circular orbit around Earth. b. Electron in circular orbit around nucleus of atom . c. Snowboarder slides over...

Homework Statement A boy skateboards down a curved playground ramp. If we treat the boy and his skateboard as a particle of total mass m = 25:0 kg, he moves through a quarter-circle with radius R = 3:0 m. He starts from rest at point A and there is no friction. (a) Find his speed at the...

I'm trying to figure out a typical range of physiological concentrations for pharmaceutical drugs. I'm looking through papers that report candidate drugs administered to cell cultures; these papers report LD50 concentrations anywhere from 1 to 100 μM. I don't have any pharmacology experience so...

Hello, I was wondering if someone could explain part of the solution to this problem for me. http://img706.imageshack.us/img706/5517/disksproblem.png To the right is the Free Body Diagram of Disk E, and I can draw the forces on there well enough. But I really do not understand how they...

I would like to a complete details on rigid body motion.

Homework Statement Note that the FAQ is not clear if I am required to use LaTeX for formatting formulas. I have not used LaTeX, but I will retype my question if I am violating the rules. Please let me know :-) Non-extensible cable attached to ceiling. Cable goes down, around a pulley and...

The hair on my head grows longer and longer while other hairs, like arm hair, only grow to a much shorter length. Why do certain hairs on the body grow only to certain lengths? How do the cells know when to stop? Thank you! →

Hi to everybody Homework Statement Well I need to identify the forces acting on the bodies using free body diagramas, it´s not necessary to calculate anything, it´s only to learn about free body diagrams. I will write my thoughts about the FBD and I will appreciate a lot if you see that I´m...

Just a question about simple moving body exercise. With no acceleration. Body moves with speed 15 m/s, time 12 seconds, mass 0.8 kg, and the force have a side effect 5 Newtons. Firstly, F=mg, so 0,8*0,98.Then I calculated the actual moving direction's force by pythagoros, that's 0,95N...

I was thinking about the rotational kinetic energy of fluids the other day and I realized that I have a huge gap in my knowledge of physics. Why doesn't rigid body rotational kinetic energy (KE = 1/2*I*ω^2) not apply to fluids or deformable bodies (it should at least be proportional to that...

Homework Statement I´ll use a picture to show the problem: Homework Equations Sum forces=0 Sum Moments=0The Attempt at a Solution Basically I´m not sure about the forces on the free body diagram and I´d like to talk about them. Assuming that P is not acting, and the body is masless...

The attached image shows a diagram of the problem. I am trying to calculate the Compressive force in the piston (B). Would the methods shown work for finding the Comp Force? Thanks

A hand supports two books, ma and mb, with ma on top. The hand accelerates the books p and to the right, with a pushing force directed 64° above horizontal. Assuming the upper book does not slip, draw a free body diagram for each book. My attempt:

Homework Statement A 105 kg acrobat jumps up off a platform at a velocity of 2.50 m/s and lands on a teeter-totter 3.00 m below, where another acrobat is waiting. If the waiting acrobat has a mass of 62.5 kg, how high does she get? Homework Equations KE=(1/2)mv^2 PEg= mgh The...

Hi All, I am an old dog, and rusty propeller head. I am having the most difficult time figuring out the forces on a pulley system I am working on. Can someone please review my sketch and tell me if I am even close. I would accept any suggestions and direction. Much Obliged -Steve

Homework Statement I have found the question I am having trouble with here: http://www.chegg.com/homework-help/questions-and-answers/block-mass-m-rest-surface-incline-adistance-h-10cm-base-height-incline-ish-50cm--coefficie-q218123 Homework Equations See below The Attempt at a Solution After...

After looking at where the isogravitational point between the Earth and the moon was, I thought about practically what sort of speed you would want to cross it at. Of course, if time is not a factor, I imagine you would ideally want to expend as little fuel possible in getting from planet to...

Homework Statement An 82 kg couch is being pushed with a force of 56 N at an angle of 40 above horizontal. If the coefficient of friction between the couch and the floor is 0.051, what is the acceleration of the couch? Homework Equations The Attempt at a Solution

When we see the black body radiation graphic (intensity vs frequency), we could say the spectrum emitted by a black body is not discrete, it's continuous (as all the frequencies are emitted). How can this be possible? If we have a black body made of Sodium, wouldn't the spectrum have only...

Hey guys; I am new to the forums. I am an effects artist who's working a Rigid Body Dynamics project and I may be able to use some of you guys' expertise while I'm building these simulations. As I stated above, I'm doing R&D for a deformation system I'm working on. What I want to do is...

In a river, water flows so how does it resist freezing? Or does it freeze at the same rate just that at the point where the cooling agent is at, the water keeps getting replaced. So the average kinetic energy of all the water molecules drop so as a whole the temperature drops? But a river is...

You mostly hear about electrons as being the vehicle of an electric current because we think of wires and metal. However, if an electric current traveled through the human body, it would be in the form of ions, right? But what happens at the interface between body and wire? I am guessing that...

I used mathematica to solve a restricted 3 body problem and was able to export my position data at different time intervals. How can I find my velocity at that final location?

This has puzzled me for a while now: A friend of mine has been told he has an auto-immune disease that has attacked his right eye - something called ocre or maybe just ocr ? If my understanding was correct that an auto imune disease can attack certain types of tissues why wouldn't he...

When a metal gets polarized it looks like this: http://postimage.org/image/bkdw8ttgn/ However, only the electron moves towards the positive ion. Why is this so? As both experience an equal force despite the different accelerations, shouldn't both the positive ion and negative electron come...

Can someone explain to me what is the wavelength of body heat? Since visible light is between 400nm - 700nm. Is body heat wavelength above 700nm? What is the wavelength range of body heat in respects to nm or m? And lastly are Infrared cameras made with Avalanche Photo Diodes? like the one...

Hello all, I'm currently a undergrad university student doing research and I'm anaylising some position data. The data is a time-series' of Eastings (x) and Northings (y) for two points (P1, P2) on a rigid body in motion (T, E1, N1, E2, N2), with a position reported every 1 minute. I know...

The wind is blowing with a force of 48 N against a kite that Taylor is flying, so that the tail of the kite makes an angle of 24° to the ground. I am just really confused on this, I attacted the solution would anyone mind explaining it? I have no idea on how to get this

For the attached picture I need to draw a free body diagram for the structure supporting the pulley. At the fixed end (left), there would be a vertical and horizontal reaction force as well as a moment. I am not sure what the forces and moments would be for the part connected to the...

Homework Statement A retarding force is applied to a body moving in a straight line so that, during an interval of its motion, its speed v decreases with increased position s according to the relation v2=k/s, where k is a constant. If the body has a forward speed of 1.8 in/sec and its position...

The speed of a body mass m = 1.6 kg moving in a straight line varies smoothly. It is measured five times, at two second intervals. The values are 7.00, 7.77, 8.89, 9.80, and 10.50 (m/s). What is the maximum value of the force acting on the body? I tried taking the average acceleration of the...

I was studying De Broglie Theory in which all bodies in movement have a de broglie wavelength associated with it. But what it means? The body's speed (Vb) is different from the wave-associated speed (Vw) Vw=λ f and Vb ≠λ f Which wave is that? Is it the wave emitted by the body as it is in...

Does anyone know why the resonant frequency of a grounded human is smaller when ungrounded?

Homework Statement A cavewoman is dragging her 65.4 kg mate home, up a gentle 10° incline. The co efficient of friction for skin on oil is 0.40. What is the minimum applied force she needs to keep the neanderthal moving with uniform motion? Homework Equations ff=μFn fg=mg fnet=ma The...

Is the Pineal Gland behind the Body Of fornix? I look at so many photos and it look like it is right behind the Thalamus but inside the body of Fornix?

2 Questions about statics of rigid bodies Homework Statement A cable of length 8.5 m is attached to the two posts as shown in Fig. 6. The crate has a mass of 1000 kg. Find the x and y components of the forces exerted by the cable on the eyebolts and find the tension force in the cable. The...

In the framework of Classical Mechanics,there is no problem in the rotation of rigid body.But I want to make the concept about rotation more clear. About rigid body ,there is no vibration;it would only rotate and translate.We can easily distinguish translation from rotation in rigid...

Hi, I'm trying to understand black body radiation but I have two conflicting descriptions (both reputable sources). Maybe both are true, but I need some clarification please: 1. A black body is a perfect emitter – it will emit equally well at any wavelength. 2. The black body re-radiates...

If, in a problem, I want to know if a given force is body force or not, what should I do? for example- a rod rotating about an axis, how will I know if the centripetal force is Body Force or not? (body forces are those forces which depend on volume)

What is the main difference between Solid body and Rigid body ? Can you give me example some of them !

In the above figure, what would be the time period of the body(in red) under gravity, neglecting any non-conservative forces? And what do call this type of situation? A gravity well or sth?

hi All, We know from QM that black bodies at temperature T emits light in a well stabilished patern. Now what if the body has color? Which is the emission patern of a green snooker ball for example, at temperature T? When scattering white light we see this ball green because it absorbs...

I have a beaker with a liquid of density rho, and weight = W now I throw into it s Bob say, of density rho' and weight=w. can anyone explain what will be total new weight,with all forces explained for the cases: body floats. body sinks

Homework Statement Problem figure The rigid body assemblage shown in the figure above, has a force P(t) acting upon it (varying with time). Pick a generalized coordinate such that a single degree of freedom equation of motion can be written. There is a black, massless, rigid bar. Call this...

I want to output an excel file with the results of the trajectories of a two body problem, with initial position and velocity. But my program is not compiling. Any suggestions/problems that you can see? #include <iostream> #include <vector> #include <fstream> using namespace std...

Hi guys new to the forum - sorry if I'm not as advanced as you lot :-p I'm currently only at A Level in my adventures of Physics! (I didn't think this would fall under homework help, I apologize if it does) Anyway, tomorrow in school there is a house technology project, and I've been entered...

Hi, how to calculate the force on a charged conductive body (ball), when that body is between two parallel plates (+V, -V) (see image), ooh and I am calculating numerically. I would first calculate the surface charges on the conductive surfaces (2 disks + ball), then calculate the potential...

Homework Statement Homework Equations The Attempt at a Solution I found out the distance between the star and companion which I calculated as 1.11x1010m (Ignoring the mass of the companion).Then I calculated the radius of the stars orbit, using r = vt/2∏ since vt =...