Speed Definition and 1000 Threads

I was curious if the relative speed of an object can exceed the speed of light. Specifically, I am curious about the following thought experiment. I am not a physicists (and if I were asking the following would make me a poor one) and it has been 20 years since college physics. If a vessel is...

I've got a quick question on the relationship between the kinetic energy of individual electrons and the total electrical energy they create. I have a radioisotope - a beta emitter - which produces electrons with around 1 MeV (1.60218×10-13 Joules / 4.45049×10-17 Watt-hours) of energy. I keep...

a) the EMF of ℰ induced on The Wire, as a function of the speed 𝑣of the wire you can find it. b) flow induced in the wire𝑖, 𝐶, 𝐵, and are denominated in 𝑙 𝑎 (𝑎= the acceleration of the wire). c) find the magnetic force acting on the wire in𝐶,𝐵, 𝑙 and𝑎. d) 𝑎 acceleration, 𝑚, 𝑔, 𝑙, and are...

Hi, I read the Feynman's book about the quantum electrodynamics and I realized, that he was talking about the different speed of photons. I know, that the light travel's "slower" in a material, but he is also talking about the different speed of photons. I read on the web, that some photons...

unsure

I'm confused as I'm aware speed is directly proportional to the EMF, but is it proportional to the voltage as well? If the speed of a DC generator is halved and everything else is remaining constant the EMF will have so will the output voltage half

Is this correct?

Let say the object explodes to three identical parts A, B, and C and initially the mass moves to the right before explosion. To obtain maximum possible speed (I assume C is the one with maximum speed), I imagine C should move to the right and A and B both should move to the left. Is this...

Let: Smaller block = m1 = 1 kg Large block = m2 = 2 kg Coefficient of friction between the two blocks = μ1 = 0.2 Coefficient of friction between larger block and floor = μ2 = 0.3 Tension connecting two blocks through two pulleys = T Angle between tension and horizontal = θ = 37o Friction between...

I am learning about hypersonic flow now and there seems to be a lot of discussion about the effects on oblique shock as the Mach tends to be very large. I was wondering what happens to the normal shock as the Mach number tends to be high and I can't seem to find anything about it. Is it because...

Hello All :) I am a student of mathematics, but I have only one semester of physics in college. I can't solve one with homework. Will there be anyone wise who can solve this? The task is as follows: Calculate: at what height the artificial satellite must move (orbit height): geostationary...

Hey I am trying to learn how waves move in time and I am not sure how to solve the following question. Can someone please guide me through it.

I require a small conical spring to open from its compressed pancake height of its wire diameter to a free length of 11mm > 0.2 seconds (20 milliseconds) The large end outer diameter = 7.80mm. The small end inner diameter must be greater than or equal to 2.75mm. The conical's spring's will be...

The centre of mass of the rod would be at the middle of the rod i.e. at l/2=[50*10^(-2)]/2 The force responsible for torque will be acting downwards = mg The Torque = mg*l/2*sin(30) =mg*l/4 We know that Torque=I*alpha Hence alpha = mg*l/(4*I) Moment of inertia of rod about the end= ml^2/12 +...

I honestly have no clue where to start, any help would be great.

I apologize if this question is in the wrong forum section - but I could not find a proper place for what is a basic question or perhaps a nonsensical one. Is the reason why an object cannot travel faster than the speed of light because the object itself is ultimately made of waves? Is the...

A particle ##p## is moving with a velocity ##u\hat i## with respect to S ... The velocity of ##p## with respect to S' is then ##-c \hat i##... Another part... Similarly taking the velocity of particle ##p## with respect to S' as ##-c\hat i## the velocity of ##p## with respect to S is then...

I've found I to be .167 using the potential and resistance. I also found the volume by multiplying the cross-sectional area by the length (?) and then dividing the # of conducting electrons into that to find packing density (n). To find drift speed, I would also need the area of the block as...

Summary:: The Hot chocolate effect is an investigation that extracts the essence about the effects on speed of sound. This is carried out in this sequence: A cup filled with liquid is continiously being tapped from the bottom. Meanwhile, a disturbance in the longitudinal sound waves is being...

The Wikipedia article on Lorentz transformations is a bit confusing by its using speed and velocity almost interchangeably: of course γ (Gamma) stays the same, but (letting c=1) t'=γ(t-vx) , then if this is v⋅x, and x stays the same, then there would be a difference if something were going away...

Time as we perceive is not a universal constant. It depends on the speed of the bodies and the distance between them.

My attempt, pictorially it looks like I am confused with the questions (a). Does the positron emerge from the field at x =0? There is no potential at x=0, so the positron will continue with the same speed hence its motion is not reversed. For the (b). The maximum volt is 200V, if i apply the...

Without assuming a universal speed that is constant in all inertial reference frames, is it a necessary consequence of Galilean symmetry that interactions are instantaneous? If this is the case how can we prove this?

so I was recently studying some ray optics and then suddenly a weird question came across my mind I just don't know if it's the correct thread to ask but let's continue anyway So the question is : suppose there is a spaceship traveling at light speed and someone fire a laser inside it what...

I've read a couple of other topics on the Physics Forums about the lumped circuit abstraction requiring that signal timescales (i.e. the period of the highest frequency signal component) be much longer than the propagation delay of the signals though the circuit and that the wavelength should be...

[Mentors' note: Split from https://www.physicsforums.com/threads/is-there-a-thought-experiment-to-show-that-the-speed-of-light-is-constant.986641/] If I could provide you with a device to measure the speed of light, and the accuracy can reach 0.01 m/s, what would you do?

I know the amazing thought experiment by Albert Einstein with the two light clocks. (The observer at the train station has a light clock and the person in the train.) It's amazing because you can even deduce the formula to calculate how fast the clock in the train goes. But this experiment...

So thing that confusses me, is what is the difference regarding the calculation of speed and velocity? In think I should use the formula I wrote above to find the average velocity, but I don't understand what the formula for average speed will be then. By the way, when using the formula above...

On the image you can see a photon starting at point A at t=0. The photons travels along the sine function and arrives point C. I knot that this takes T=λ/c. But this is the time for a object traveling directly from the origin to point C and not along the sine wave! If the photon travels...

Lats say that i am moving on spaceship that moves 50% of the speed of light And this spaceship is on a planet that moves in speed of 50% of the speed of light . And we have one clock on the spaceship ,clock number one, and on the planet we another clock,clock number two. And on difference...

there is many analog dividing machine that base on time counting . so does this machines work faster on height speed system such as Particle Accelerator it may help in decryption of public encryption and other coculation . It looked at relative calculator and in the speed that close to the...

I am using the Stanford “Dynamics: Inverted pendulum on a cart” document, https://web.stanford.edu/class/me161/documents/InvertedPendulumOnCartSolution.pdf, as the basis for the Arduino c code. I need help with the term Fc (Feedback force on the cart A) because the motor I’m using is a stepper...

A lighthouse is located on a small island 16 km off-shore from the nearest point P on a straight shoreline. Its light makes 5 revolutions per minute. How fast is the light beam moving along the shoreline when it is shining on a point 3 km along the shoreline from P?

It appears that the most probable energy level according to the Maxwell-Boltzmann distribution is not equal to the most probable speed squared multiplied by ##\frac{1}{2}m##. The most probable speed has a different value. $$E_{max} = \frac{k_BT}{2}$$ $$v_{max} = \sqrt{\frac{2k_BT}{m}}$$ I am...

Hi PF! I'd like to test how fast my cpu clock speed is. Any recommendations with benchmarks so I can see just where I fit?

As much as i search Google, in an effort to find out how exactly the constancy of speed of light was historically deduced before 1905, from Maxwell equations or by any other means, i am not able to find such an explanation. In all of the search results that i could find, it is just stated that...

[Moderator: moved from a homework forum. This does not sound like homework.]Homework Statement:: Why is it the case that when the low-frequency response is to the right of the M = 1 line that the 'speed of response is slow'? Relevant Equations:: M-cirlces Hi, Hope you are doing well and...

I have successfully composted before,(for planting) but is there a way to speed it up, maybe with mycorrhizal? (I hope this is the right section) I live in a hot (35C-48 C or 95F-120F) dry environment and I know to keep it damp (not Dripping) and well mixed (add air)

Here is the Q Very unsure about how to approach this question but this is what I have tried Any help would be really appreciated! Thanks

I've always thought that light could possibly be transmitted faster in one direction than the other depending on the velocity of its container - despite what the current understanding of physics says! The problem is that its very hard to prove, and to this end I've read through all the...

Hi, I read various threads in PF about the concept of invariant speed and the speed of light in vacuum that in our universe happens to be the same as the 'invariant speed'. My doubt is about the speed of the light in vacuum as measured from a non-inertial frame (basically in the context of SR...

I recognise that the normal force must alwayss act towards the centre of the circle loop, as the rail always has to be exertign a pushing force on the car/carriage in order for it to follow the trajectoryof the loop. However , I cannot understand why, the reaction force has to be greater than...

Which one does it mean: "phase velocity" or "group velocity" or "speed of the wave front"? In the postulate of constant speed of light .

Apparently, right now the Earth is spinning at 1,000 mph! From https://www.space.com/33527-how-fast-is-earth-moving.html "Earth's spin is constant, but the speed depends on what latitude you are located at. Here's an example. The circumference (distance around the largest part of the Earth) is...

Hello, I consider to be in a relativistic area, where an object is moving very fast, seen from our Earth, at a speed v where v is less than the speed of light c. I have considered the following equations (relativity equations) : T = β * t M = β * m L = l / β β = 1 / (√(1 – v2/c2) )...

What is the equation/formula for the Speed Of Light? E=mc²? I thought it would be simple to find in a search.

Hello everyone! Let's say that you were to attempt to go as fast as possible on a spaceship with the mass of an average car in an absolute perfect vacuum. What I am wondering is, that if you were to reach a certain speed, and stop applying energy to this imagined spaceship, would the spaceship...

I get two different answers even the area of the graph. I think there is something wrong with the equation I constructed for average speed part. I know the method 1 is correct. But I'd like to know why the average speed cannot be used. And why I get two different areas for the graph Thank you