Reference Definition and 1000 Threads

I'm hoping you can help with a debate I'm having with a friend regarding whether throwing a ball in a headwind is the same or different from throwing a ball from a moving platform (lets say an open boat). If you want some numbers, could you please work with these: For the static throw, can...

Hi, I've seen the forces in a turn depicted two different ways: http://selair.selkirk.ca/Training/Aerodynamics/images/lf-turn.gif http://www.free-online-private-pilot-ground-school.com/images/forces_during_turn.gif Which one is correct? I think the first one would be since it's...

Previously, before getting into relativity, I've always thought of a 'reference frame' of basically an "observer carrying a coordinate system" - where I thought of an observer as anything which could record information of positions and velocities of particles etc. Now, however, I'm reading a...

If any of you have the Third Edition of Classical Electrodynamics by John David Jackson, turn to section 11.8, as that's where I'm getting all this from. If not, you should still be able to follow along. In said section, Jackson gives us this equation that relates any physical vector G in a...

I am working on a concentrated solar heater using a linear fresnel reflector. I want to learn how I can harness this heat to power a cooling system, preferably with minimal use of electricity. I am in India, so this has a huge ground for application. I was looking at ideas here, and while...

Homework Statement In frame F there are two lights on the x-axis at D and -D (D=0.6x10^9 m ) which flash simultaneously when t=0. There is another frame F' which moves at v=0.8c in standard configuration with F. I need to work out when observers standing at the origin of both frame F and F'...

I have two rigid bodies floating in space that are kinematically constrained by a joint (think of a 2 dof link mechanism floating in space). I have a body fixed reference frame on each rigid body plus the global space-fixed reference frame. The first rigid body is in the space-fixed...

I'm attempting to build a line follower robot and I'm currently in the process of building appropriate models. For the control system I need to define a coordinate system. The most convinient coordinate system from many point of views would be a coordinate system that moves along and changes...

What is the criteria to see the latest state of some object which exists after all the previous states in other reference frames? For instance, one observer may see a plane coming off the airport as 'present', other may see 'its flying' as present, but what is the criteria of those reference...

Haefele and Keating flew an atomic clock from the west coast to the east coast in 1971 and then they flew it back. The east going clock lost 59 +- 10 ns and the west going clock gained 273 +- 7 ns. What I do not understand is why they used the center of the Earth as a reference frame, and not...

Hey everyone, I started reading up on GR a couple of days ago, and I'm somewhat stuck on the concept of a free-falling IRF. I understand that an observer on a free-falling small spaceship would experience the laws of physics in a rather simple form, eliminating the need for a force of gravity...

Dear folks, I decided to prepare myself for taking the GRE on mathematics and physics next year, and coming from a non-traditional path (undergrad in music, basically self-taught in scientific matters), I'd like to ask you about some reference books and, thus, about the actual level of each...

I've been looking for a good reference for luminescence spectroscopy but I haven't found anything. Could anyone please help me?

Homework Statement Generic collision question. For example, let's say you are asked the following question: Object 1 is 10kg and is traveling at 10 m/s [right] Object 2 is 5kg and is traveling at 2 m/s [right] Find their final collisions after impact Homework Equations m1v1 +...

Homework Statement Imagine that a circular disc is rotating with a frictionless ball on it( ball is not at center of the disc) If we observe the motion of the ball from the rotating frame of reference, then how can we describe its motion? Homework Equations The Attempt at a...

for the 1st two I used v is to the reference frame = 37m/s- -35m/s=72m/s a)ball=[(m2-m1)/(m1+m2)]v bat=v2=[(2m1)/(m1+m2)]*v b) I do not know how to solve for part b. The Attempt at a Solution

So I would agree that it has a uniform tangential velocity but would the centripetal acceleration of the Earth put it in a non inertial frame.

I got stuck going over the derivation of fictitious forces in rotating frames. see specifically http://en.wikipedia.org/wiki/Rotating_reference_frame#Time_derivatives_in_the_two_frames this page to see the proof I'm talking about (sorry i'd love to be able to explain it by myself but...

How does the concept of frame of reference apply to quantum mechanics? Classically something can be a frame of reference as long as it is not accelerating. I often picture in my head an atom with the nucleus fixed and the electron cloud surrounding it. Would it be possible to describe an atom...

Suppose I'm considering particles of mass \mu_i, 1 \leq i \leq 3, located at positions r_i. Suppose I ignore the potential between \mu_1 and \mu_2. Then the Hamiltonian I'd write down would be H = -\frac{1}{2\mu_1}\Delta_1 -\frac{1}{2\mu_2}\Delta_2 - \frac{1}{2\mu_3}\Delta_3 + V_1(r_3 -...

Suppose we have two frames of reference, with one being accelerated (not inertial). This could be you standing on the platform of a train station as a train in front of you is starting. From the train's point of view, you are accelerating, but one obviously knows that it is actually the train...

Time in the "reference frame" of the photon and as well curved spac Hi there! I understand the tendency of physicists to stick to the math, and the logic itself, and to often avoid attempting to conceptualize a process or law, but that's kinda the opposite of what I'd like to do here. I...

someone please help me out with this question: You are in an elelvator that is able to travel up and down a mineshaft. a load is hung from the ceiling inside the elevator on a massless string. You find that the tension in the rope is 10% less than that of the weight force of the load. what...

Hi everyone. I rediscovered a question I caught in High-school that I never encountered a answer to. Given a spaceship going back and forth into space, during it's travel it accelerate close to c relative to earth. At an appropriate distance it breaks and returns in a similar fashion. My...

I found this extremely handy reference on Black hole calculations and models to measure black hole accretion disk/jets. The article also covers several types of BH non rotating and rotating. Methodologies that can be used to distinquish between Neutron and black hole event horizons...

My understanding is that as I move, from my FoR all objects and space itself (according to Einstein) contract along the direction of my movement. This length contraction occurs for all space and objects in front of me for an infinite distance. Furthermore, relative motion is relative, and the...

In the design of a State Space controller using state feedback the input to the plant is given as (where y=x & D=0): u=-Kx If there is a "reference input" then it would be: u=-Kx+r So the state feedback without the reference input simply drives all of the state variables to zero. When there is...

Hi gang, I am hoping you can clear something up for me. When evaluating the potential of a solid sphere, I find myself confused about the volumes used such that, \phi = Q \int_{\infty}^R \frac{1}{V_1} r^2 \sin(\theta) \, dr \, d\theta \, d\phi + Q \int_R^r \frac{1}{V_2} r^2 \sin(\theta) \...

Is there a "Stuff -> Materials it's made of" reference around? This is somewhat a borderline question, but I guess the Materials subsection of the forum is the best place for it. Yesterday I broached a bottle of wine, one with bubbles (that's the most elaborate description my wine expertise...

My question regards how the approximation becomes an equality.

I'm working problem from the upper division classical mechanics course on MIT OCW. No solutions are available. This is form the first P-set, question 4. Homework Statement A particle moves in a two dimensional orbit defined by x = A(2αt-sin(αt)) y = A(1-cos(αt)) Find the tangential...

As I understand it, Einstein's dismissal of the "luminiferous aether" was based on his discovery that there is no universal frame of reference, i.e. that no frame of reference is privileged in relation to all other frames. My question is whether this principle can also be stated in the inverse...

Homework Statement Is the kinetic energy of an electron the same in all frames of reference? Homework Equations I think that the kinetic energy of an electron is E = hc / λ. However, I am not sure: I got this from searching Google rather than learning it myself. The Attempt at a...

Why can we not CHOOSE a reference frame locally and treat everything inside of it as an inertial reference frame. For example in a classroom, the classroom is moving with the Earth and so is a ball rolling down the class. Because they are both equally moving due to the Earth's rotation, why...

I've been giving some thought to the new scientist article about the equivalence principle. What initially seems like a very simple issue is remarkably tantalising. (please note- I'm not a physicist so this may be quite stupid) This led me on a little to the question of gravity and direction...

I'm currently teaching myself some QFT trough Peskin and Schroeders Introduction to QFT and I've noticed that in several arguments they rely on appealing to the Born approximation of non-relativistic QM scattering theory. For example on page 121 equation (4.125) they appeal to the scattering...

So sense speed is relative, could I observe something traveling faster than light? Like in a car, when I see oncoming traffic it appears much faster, so could I not be traveling at, say 1/2c and observe somebody approaching at 1/2c therefore moving at 1c relative to me?

I know that you're going to probably say that a frame of reference doesn't make sense for light, but I've uploaded a discussion (warning: has profanity) from another website (reddit.com) and I'm curious to see if the user Imhtpsnvsbl makes a valid point.

Hello, I have a little three-body (well n-body but let's just worry about 3 now) simulator. I input six Keplerian orbital elements (period P, eccentricity E, inclination I, longitude of the ascending node W, argument of periapse w and initial true anomaly f). They then get converted to...

Homework Statement In the laboratory frame, event 1 occurs at x = 0 light-years, t = 0 years. Event 2 occurs at x = 6 light-years, t = 10 years. In all rocket frames, event 1 also occurs at the position 0 light-years and the time 0 years. The y- and z- coordinates of both events are zero in...

Hi. I was recently calculating some centroids and I was wondering if the point were I choose my origin affects the centroid position. I.e., if I choose my origin at a massive particle, will the centroid be the same as with any other reference frame? Thansk :)

Can anyone give me some advice on where I should take my points of reference when using bernulli equation. I know the point will vary according to the problem, but can one say, always begin looking for this and that and apply the equation... Then move to this and that, etc

I need some reference books on the following... My 3rd year 2nd sem Undergraduate physics syllabus has a part like this- (I have 2 sem q.m., 1 sem special relativity as background.) The nuclear two-body problem and simple theory of the deuteron. Elementary particles: Baryons...

Homework Statement K mesons (“kaons”) are unstable particles composed of a quark and an antiquark. They can be produced copiously in energetic collisions between stable particles at accelerator laboratories. Soon after they are produced, kaons decay to lighter particles. One type of kaon...

Due to my job and other classes, I've been studying ahead of my class by myself to not fall behind and I'm not sure if I'm oversimplifying this in my head and not really grasping the idea. Newton's First Law of Motion states that an object with a net force of zero stays in constant motion (or...

hi guys, i have a basic question on special relativity.. if the inertial reference frame denotes the frames that holds up the Newtonian 1st law, then can Earth be an inertial frame? i mean it changes direction of velocity as it moves in the orbit around sun, so its not in constant velocity ...

Homework Statement Suppose you have a spaceship and in the spaceship is a block on an frictionless incline. Initially, the spaceship is at rest on the Earth's surface. The astronaut in the spaceship observes the block sliding down the incline with acceleration Mgsinθ . Now consider that the...

First, a brief description of myself: I'v gotten my associates degree in Automotive Technology/Repair, with perfect scores. ASE certified. But I have always been an aspiring Mechanical Engineer, with assisted passion for technical/hands-on intuition. That is why I studied a vocational field...

What is an inertial reference frame?How are positions,velocities and accelerations changed when switching between different inertial reference frames? r=rx i + ry j + rz k Inertial reference frame:It is a frame of reference where Newton's laws of motion is valid.No fictitious...

I know total energy is conserved, but does this mean that different frames agree on the total energy of a particle? I'm assuming they don't agree on energy, because if I measured the total energy of a particle moving relative to me (which would equal the rest energy plus its kinetic energy)...