Rest Definition and 558 Threads

The Schwarzschild metric (ignoring the angular parts) looks like this: ##ds^2 = (1 - \frac{2GM}{c^2 r}) c^2 dt^2 - \frac{1}{1 - \frac{2GM}{c^2 r}} dr^2## The Rindler metric in 2 spacetime dimensions looks like this: ##ds^2 = (g r)^2 dt^2 - dr^2## They are very different, but they have some...

Homework Statement An Electron with an initial speed of 500,000m/s is brought to rest by an electric field a)did the electron move into a region of higher or lower potential? I b) what was the potential difference that stopped the electron? Homework Equations ΔV=ΔU/q ΔU=-W The Attempt at a...

Can we truly have a rest frame or should it be a close to rest frame? Even if I'm stationary and sitting on my porch and the observer in the car passing is moving, I'm still not at 0 velocity. The Earth is moving at 67,000 mph and the galaxy is moving at 250,000 mph. I'm never in a single...

Homework Statement In a collision between three identical steel balls A B C A comes to rest and B remains stationary, while C rolls off. In terms of the Forces acting, explain how Ball A came to rest and why Ball B remained stationary. Homework EquationsThe Attempt at a Solution Well what I...

Hi. If the 4-momentum in SR is given by p = m γ(v) ( 1 , v ) then in the rest frame of a particle the 4-momentum is ( m , 0 , 0 , 0 ) using c=1 units. This uses the fact that because v = 0 then γ(v) = 1. I'm confused about this last sentence. The gamma factor is used for the relative velocity...

I'd like to ask an specific question. If c changes (for whatever reason*), does the rest mass of a given particle changes, asuming E is conserved? Let's say, for a given particle, the following initial condition: Placed in a vacuum**. Rest mass m0. Particle's energy E. Propagation speed of...

dear sir, light travels with constant speed of 3 x 10^8 m/s. does that mean light is in absolute motion irrespective of the its source?

In STR we measure motion relative to a observer, and the he is rest respect to him. We make coordinates relative to "a rest frame" , that is the observer. In GTR ,all motion are calculated from which frame?

Homework Statement In frame S particle 1 is at rest and particle 2 is moving to the right with velocity u. Now consider a frame S 0 which, relative to S, is moving to the right with velocity v. Determine the value of v such that the two particles appear in S' to be approaching each other with...

Homework Statement 14.27 The 2.5-kg weight is released from rest in position A, where the two springs of stiffness k each are undeformed. Determine the largest k for which the weight would reach position B Homework EquationsThe Attempt at a Solution Hi. Can you check if I am going at...

Homework Statement 14.10 Solve Prob. 12.47 by the work-energy method 12.47 When the 1.8-kg block is in the position shown, the attached spring is undeformed. If the block is released from rest in this position, determine its velocity when it hits the floor Homework EquationsThe Attempt...

Dirac's rest mass seems to be expressed as a fourth dimension. If we were to try to include this rest-mass dimension into Minowski space time, could it be expressed as a distance in space? S^2=x^2+y^2+z^2+(rest-mass dimension)^2-(ct)^2?

Homework Statement A solid cylinder rotates till it comes to rest. It has inititial angular velocity. To stop the drum a mass m ishung the belt which has a friction coefficient with the drum material as u we have to find no of rotationd all the data is known and correct Homework Equations...

Homework Statement 13.54 The pentulum is released from rest with θ = 30deg. (a) Derive the equation of motion using θ as the independent variable. (b) Determine the speed of the bob as a function of θ. The solutions given in the textbok are a) ##\ddot θ = -4.905sinθ rad/s^2## b) ##6.26\sqrt...

I am trying to understanding magnetism and I've been running into this thought problem A particle a in a magnetic field B responds with Force F=|q|v x B. frame S: The field is B1, caused by a moving charge/s - current at speed v. the particle is at rest, F=0. frame S' moves with speed v/2...

Homework Statement gearbox and flywheel are as shown in FIGURE 4. The output shaft rotates in the opposite direction to the input shaft at 5 times its speed. The gearbox has an efficiency of 92%. If the flywheel is solid, has a mass of 50 kg, a diameter of 1.5 m and is to accelerate from rest...

Hi! I'm thinking how would the velocity of a sphere change if it falls from rest in a tall beaker full of oil. I know that the direction of acceleration is upwards, and the acceleration should be decreasing at a decreasing rate. But how would the velocity change if the velocity is initially zero...

In all the derivations of E2=p2c2+m2c4 ,that I've stumbled on, it's assumed that the rest mass energy is m*c2 just because kinetic energy is mc2λ-mc2. Was it originally assumed? If so, can someone explain me why is it a logical assumption? Are there any derivations without such assumptions?

I was reading about Rest Energy and came across this line: "In special relativity, however, the energy of a body at rest is determined to be mc2. Thus, each body of rest mass m possesses mc2 of “rest energy,” which potentially is available for conversion to other forms of energy. The...

1. Homework Statement A rod (m=6kg, L=3m) at rest on ice (μ=0) is struck by a piece of clay (m=1kg, V=5m/s). The clay sticks. 1) What is the Velocity of the center of mass after the collision? 2) What is the Angular Velocity of the rod following the collision? If the clay did not stick but...

Why is it that the fundamental harmonic is louder than rest? If energy is the same as frequency surely the greater the harmonic the louder it is. Also what does amplitude represent in waves?

The stress-energy tensor of a perfect fluid in its rest frame is: (1) Tij= diag [ρc2, P, P, P] where ρc2 is the energy density and P the pressure of the fluid. If Tij is as stated in eq.(1), the metric tensor gij of the system composed by an indefinitely extended perfect fluid in...

May i know a mat put on the ESD floor is called floor mat or foot rest? There is one understanding that the floor mat is used to put on non-ESD floor. Is this correct? Thanks, Priscilla

The energy equation for a particle contains the rest mass and momentum. If the momentum is zero, all the energy comes from the term mc^{2}. That means the particle still holds some energy. What is the form of that energy? For example string theory explains particles as vibrating strings, and I...

We are giving a particle with mass 400 Mev/C2 and 200 MeV KE. What is the Energy of the particle? Is it 600 MeV or 200 MeV?

Homework Statement I have attached the known information. When the truck is at rest, will the crate also be at rest or will it slide downwards? Homework Equations Sum F_y =0 G_max = (my_s)*N G_min = (my_k) * N The Attempt at a Solution I did a Free body diagram on the crate (see the attached...

So from what I've heard, the rest mass of a object increases when the object's internal energy increases. So a clock that is ticking has increased rest mass vs the same clock that is completely still. But doesn't the clock have moving parts that give kinetic and thermal energy? Then in what...

Hi! Could someone explain to me why an electron at rest without any influence from a magnetic or electric field cannot emit a photon ? Could you explain it mathematically too ? Thanks in advance...

I have solved the question below and was wondering someone can have a look at it and give some feedback, please. Homework Statement An object is pushed from rest across a sheet of ice, accelerating at 5.0 m/s2 over a distance of 80.0 cm. The object then slides with a constant speed for 4.0 s...

Homework Statement A particle is accelerated so it has a total energy of 10GeV measured in the accelerator’s rest frame. The particle's momentum is 8GeV/c in the same frame. Calculate... a.) Rest mass of the particle b.) Energy in an inertial frame in which its momentum is 6GeV/c c.) The speed...

Homework Statement Good day all! Quick question: As part of a problem statement, I'm asked to verify if the trajectory: \frac{dx}{dt}=\frac{cgt}{\sqrt{1+g^2t^2}} Is "consistent". Homework Equations None The Attempt at a Solution Im not sure what "consistent" means. Does it mean, \frac...

Homework Statement : A stick of length L and mass M lies on a frictionless horizontal surface on which it is free to move in any way. A ball of mass m moving with speed v collides elastically with the rod at one of its extreme end( as shown in the figure). If after collision ball comes to rest...

Given De Broglie's equations of a quantised wave: E = 2.Pi.hbar.c Where: E = Energy Pi = PI (Ratio of circumference to radius) hbar = Planck's constant (Reduced over 2.Pi) c = celerity, causal displacement per time interval In most texts this is summarised as: E = h.nu Where: h = Planck's...

$\tiny{205_o6_05_velocity}$ The equation for a free fall at the surface of celestial body in outer space ($s$ in Meters, $t$ in seconds.)\\ is $\displaystyle s=2.38t^2$ How long does it take a rock falling from rest to reach a velocity of $\displaystyle 25.7 \frac{m}{sec}$ on this celestial...

The energy associated with the mass of a free proton in the center of momentum frame where the proton’s momentum is zero is 938.272 (with more decimals). What is the rest energy of a single proton inside a Uranium atom? (It could be any other radioactive or fissionable element but I took...

Once I cross the event horizon of a BH, is it valid to say that I'm at rest and the singularity comes up to meet me?

Homework Statement A ball is dropped vertically from a height H on to a plane surface and permitted to bounce repeatedly along a vertical line. After every bounce, its kinetic energy becomes a quarter of its kinetic energy before the bounce. The ball will come to rest after time? Homework...

Surly the variable speed of light is a dead dog, this article says it is not, and the theory can be tested But some researchers have suggested that the speed of light could have been much higher in this early universe. Now, one of this theory's originators, Professor João Magueijo from Imperial...

How does one find the normal force when the object is not at constant movement or at rest.

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I don't remember seeing this solution to the question. Imagine an object of length d with a reflector on the far end (x=4). A moves past the object at speed a, emitting a signal at the origin in the positive x direction. A makes one pass in the +x direction, reverses and makes one pass in the...

What happens with the information about the curvature of the trajectory of a body when the body stops? We know that to assess the curvature of a path we must calculate the value of a fraction of which the denominator is speed module (cubed). But if speed module is canceled, this fraction can not...

In running my vacuum cleaner, I have noticed that the plug end of the cord gets warmer than the rest of the cord. Since the wire gauge and current must be the same through the entire length, why would this happen? I have noticed this regardless of the wall socket that I use and it doesn't seem...

Homework Statement I really don't have a homework question just a thought. Is rest energy "maximum energy" for a particle? As to say a particle at rest has a given energy, so when it is in motion it transfers some mass energy to kinetic energy, where both the mass and kinetic energy together...

This thread's purpose is to share what people are proud about in traditionally non-western countries. Or the second- and third- world countries if you prefer to call them so. They may also be small western countries that don't get frequent publicity in the media, such as Island and similar. You...

Hey guys, So I'm interested in the application of an eddy current brake system as a high intensity shock absorber of some sort. The system would consist of permanent magnets concentrated on a stationary, non ferromagnetic metal. If a sudden, intense force were to act upon the non ferromagnetic...

Homework Statement An electron is released from rest in a weak electric field given by = -2.70 10-10 N/C [PLAIN]http://www.webassign.net/images/lowercase/jhatbold.svg. After the electron has traveled a vertical distance of 1.4µm, what is its speed? (Do not neglect the gravitational force on...

I always enjoy physics questions that aren't super complicated and give me something to think about for a day or two. One that has recently come to my head is how many times will a ball bounce before coming to a rest. what formulas should I use to find this out.

Homework Statement "You might wonder how six protons and six neutrons, each having a mass larger than 1 u, can be combined with six electrons to form a carbon-12 atom having a mass of exactly 12 u. The bound system of carbon-12 has a lower rest energy than that of six separate protons and six...

Does the rest mass of an object increase when it acquires gravitational potential energy, and if so, is this the reason why Einstein believed that the inertia of a mass increases in the presence of other masses?