For simple circular motion it is common to resolve forces toward the centre and relate this to centripetal acceleration, provided that the current reference frame is inertial.
However where would such a coordinate system be positioned? Since it requires one axis passing through the line...
The man floating inside the elevator travels through space at constant velocity, and soon reaches proximity to a planet.
To an outside observer, the elevator appears to change course and accelerate towards the planet, so he reasons there is a force acting on the elevator, changing its course and...
A problem of an isolated system's velocity in different inertial systems, in special relativity
##\ \ \ \ \ ## In the inertial reference frame ##K##, the velocity of each component of an isolated system in ## x## direction is zero at a certain time.
##\ \ \ \ \ ## The inertial reference frame...
I get that the concept of relativistic mass has sort of been deprecated in physics these days and that relativistic momentum is supposed to be seen as more well useful. So let momentum equal ##\mathtt ~~ \frac {mv} {\sqrt {1 - \frac {v^2} {c^2}}} ~~## or ##~~{mv\gamma}~~##. So mass is supposed...
I) For ##A##, the positition is ##\vec r=(0;V_0 . t;0)##.
For ##B##, we have ##\vec r_A=\vec r_B + \vec r_{A/B}##, but ##\vec r_{A/B}## is equal to zero because they have the same origin, so the position measured from ##A## is equal to the position measured from ##B##
II) For ##A##, velocity...
Summary: Apparently an ice cube gains mass when it melts
So I'm asked to "Find the fractional increase in inertial mass when an ice cube melts ".
All I've got off the top of my head right now is that a cube has energy = mc^2, and then when the cube melts, energy Q = (Heat of fusion)(m) is...
I know that the entropy of a system is the same in different inertial frames. Is this still the case for non inertial frames? For example, is the entropy of a body as seen from a rotating reference frame the same as the entropy seen from a fixed frame?
I have a really stupid question.
Suppose I am in a car and the car is going around a loop.
Yes, the Earth is not inertial -- it rotates -- but let me ignore that and, momentarily, designate the Earth as inertial.
Now, we know the frame of the car is not inertial--the car is turning. We...
How we talk about referential inertial if the Earth always is in motion? Because if the Earth is in motion, everything is in motion with the Earth. So nothing is a inertial referential.
How can we talk about Newton's First Law?
Lets neglect conservation of momentum and assume that all frames of reference are inertial. Now imagine three objects: the sun, the Earth and an asteroid. In the inertial frame of the sun, Earth and asteroid are flying towards each other ( velocitys v and -v).
Now imagine you are standing at...
Hello. I have a question on inertial motion transverse to gravity force, e.g. blocks of dry ice floating on the smooth and flat floor on Earth. For simple mathematics I explain my problem in Rindler case.
Let a group of N rockets gather at origin (0,0,0,0) of a IFR and let them start...
This is probably common knowledge to relativity aficionados but at Example 7.3 in this paper:
https://www.farmingdale.edu/faculty/peter-nolan/pdf/relativity/Ch07Rel.pdf
I was surprised to read the author showing that a ship accelerating at 1g from rest for 1 hour and reaching a speed of...
I know this is a basic question, but I haven't understood deeply what a inertial frame of reference is, to be more specific, its relation with the first law of motion.
Homework Statement
A high-speed centipede in S’ is 10.0 cm long measured at rest in S’. A butcher in S holds two cleavers (A and B) 9.00 cm apart (measured in S). The centipede runs at such high speed v across a chopping block that the butcher measures the length of the centipede to be 8.00 cm...
How to find the angular speed, on which a spinning hollow cylindrical body breaks due to inertial stress(force)?
I found 2 sources(http://www.roymech.co.uk/Useful_Tables/Cams_Springs/Flywheels.html (last 2 equations) ...
Hey PF, I am working on a problem set, and one of the problems is proving that the Christoffel symbols vanish at the origin of the coordinates ##y^{\alpha}## given by the coordinate transformation: $$y^\alpha (x) = x^\alpha - x^\alpha_{(0)} + \frac {1} {2} (x^\mu - x^\mu_{(0)} )(x^\nu -...
This question concerns inertial frames.
I am aware that an inertial frame is one that is not accelerating.
I am aware of an alternative definition: it is one on which no forces are applied.
(Yes, they are the same thing.)
I am also aware of the d'Alembert "forces" that appear when a frame is...
I know that special relativity is based on the postulate that an object that travels at the speed of light with respect to one inertial observer must travel with the speed of light with respect to all inertial observers. This postulate implies that no two inertial frames can differ by a relative...
I'm not being extremely exact here, but suppose there's a puck in a board where there's very little friction. Both puck and board are at rest. Suppose the board starts from rest to some decent speed, so there's definitely this acceleration, by virtue of which (and also less friction), puck...
According to special relativity, all inertial frames of reference are equivalent for descriptions of physical phenomena. Suppose that there is a free particle in free space. Observed in any of the frames, the motion of particle can be described by a velocity, and by Lorentz boost, one can get...
My question is about some physical quantities which two observers in two respective inertial frames will find the same. I wonder are there any such quantities? Some books say force, speed of light etc are constants for both the observers. Please guide me on this.
Regards.
In Abraham Pais book (which was first published in 1982), he states the following:
"Quantum field theory has taught us that particles nevertheless have structure, arising from quantum fluctuations. Recently, unified field theories have taught us that the mass of the electron is certainly not...
Can anyone help with this please...
Would the following work?
Magnetic inertial Confinement Hybrid Fusion Reactor.
Peeta Watt lasers are focused on the plasma in the equatorial plane of the multi mega amp plasma pulse within its’ torous geometry between the center post and the merging...
Homework Statement
The position of a participle in a fixed inertial frame of reference is given by the vector
r = i(x0 + Rcos(Ωt)) +j(Rsin(Ωt))where x0, R and Ω are constants.
a) Show that the particle moves in a circle with constant speed
Homework Equations
F = mv2/r
The Attempt at a...
Hello all,
This post is in reference to a previous homework post, found here:
https://www.physicsforums.com/threads/show-that-f-gamma-3-ma.338744/
That thread is closed to further replies. Probably because it's nearly 10 years old.
That thread is about deriving relativistic force from the...
Homework Statement
3. (a) If an object's acceleration is zero in one inertial reference frame then is its acceleration zero in all other inertial reference frames? (b) If an object's velocity is zero in one inertial reference frame then is its velocity zero in all other inertial reference...
Are two objects, accelerating at the same rate, and in the same direction, considered inertial to one another? If so, I will post my resulting question. If not, it's safe to disregard this thread.
Thanks,
Jake
In Newtonian mechanics, both gravitational mass and inertial mass is m. This principle is known as the principle of equivalence. However, I heard that in Relativity, gravitational mass is γm instead of m because total energy of the particle is γmc2. But in special relativity, it is widely known...
Homework Statement
Which of these situations describes you observing from an inertial reference frame?
a. you are in the car of a train, seated at a table, and the train suddenly slows down
b. you are in the car of a train, going north, and the train goes around a curve to go west
c. you are in...
A freely falling body (falling in earth) accelerates with time. However, an object inside the body remains at rest (if it was initially at rest) or moves with a constant velocity if it was initially moving with constant velocity. In other words a frame fixed to the body is an inertial frame...
Maybe i should pose this query in a different area, but since it involves basic physical laws of motion...
Space flight? I know this should be obvious enough but i was wondering how a shuttle is capable of maneuvering once in an area with which gravity and atmosphere play too little a part on...
Hello! The angular velocity in the non-inertial frame of a rotating body of mass m is ##\Omega## and I need to find the force acting on the body (in the non-inertial frame associated with the body). In the book they say (without any derivation, they just state it) that the force is...
I would like to know what ways are there to get rid of the inertia problem when it comes to sci-fi concepts such as Iron Man and spaceships. I'm actually more interested in how could it be possible for a spaceship to accelerate to a very high G without causing its inhabitants a mass concussion...
Homework Statement
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Homework EquationsThe Attempt at a Solution
I think the two masses , inertial and gravitational are equivalent and because of this fact , the ratio of the two masses is one . The correct option should be 1) .
But the answer given is 3) i.e A statement is true and R...
For many, many years (don't ask), I've been running into the classic example of the local reference frame: the man in the box who can't tell if he's floating free in space, or falling into a gravity well.
It occurs to me that if one is in a falling box, a mass released at the top of the box...
Hello everyone. This is my first time on the physics forum, but I think I'm going to be a regular here.
I was reading a paper that outlined various ways to approach solving dynamic problems. The first approach outlined by the author is D'Alembert's principle of virtual work. In describing...
Imagine such situation:
A bus is moving at constant speed, a man is standing on the bus and is not holding to anything - he is simply standing.
Now, the bus starts breaking with constant negative acceleration and so the man will change his relative position due to the force of inertia.
Now...
I've been playing around a bit with the Kerr orbit program I wrote, and have been thinking about ways to set the initial conditions. One thing I'd like to be able to do is specify a launch from some event in terms that would be convenient for an observer at that event with some given...
Homework Statement
I was re-reading my old Relativity book (by Rindler) and taking a look at some of the problems. He asks: Using a Minkowski diagram to establish the following result:
Given two rods of rest lengths ##l_1## and ##l_2 (l_2 < l_1)##, moving along a common line with relativity...
Doesn't the postulation of the inertial and gravitational mass equivalence suggest that GR is not a complete theory? (since it also cannot be explained as a neccessity by the anthropic principle)
Does anyone know of a source, on the Internet preferably, for component inertial data for a real IC engine? In particular, what I'd like to obtain (for some real engine, any engine) are these items:
1. Piston weight (including wrist pin)
2. Cylinder bore dimension
3. Connecting rod length...
I know this is a naive question that has almost certainly been brought up numerous times before, but my search abilities seem not to be sufficient for finding a good answer, so if anyone just refers me, that would be fine. The question: Special relativity concerns comparisons between pairs of...
I have just begun my journey in Classical Mechanics with the book "An Introduction to Mechanics" by Kleppner and Kolenkow. I find myself stuck at Newton's first law. The book presents Newton's first law as follows:
"Newton's first law is an assertion that inertial frames exist."
The book also...
One particular form of the equivalence principle states that
The laws of physics for freely falling particles in a gravitational field are locally indistinguishable from those in a uniformly accelerating frame in Minkowski spacetime
My question is, does one arrive at this conclusion from a...