Speed Definition and 1000 Threads

How fast would the light travel for a SuperBig observer... immagine his head is the size of the Sun, and he is sitting in a room, then he decides to turn on the light in the room... if he is so big, would he have to wait some seconds until the light reaches his eyes? Would it mean that for this...

If light speed (not in a vacuum) was about human walking speed ... Did any sci fi writer try that?

Drive two 15m long optical fibers extended in opposite directions with a 1GHz pulse generator. The recievers at the end of each fiber are now syncronised sources of 1GHz pulses. Connect them to pulse counters, one of which provides a signal whenever a pulse train is present. Connect this...

Homework Statement As we know the Average speed = Total distance / Total time but why in the case below Distance traveled = s₁ + s₂ + s₃ and total time taken = s₁/v₁ + s₂/v₂ + s₃/v₃ How is it possible? so, altogether Vav = s₁ + s₂ + s₃ / ( s₁/v₁ + s₂/v₂ + s₃/v₃)Homework EquationsThe Attempt...

Why is the speed of light a constant?

Do we know enough of the workings of string theory to say what factors give rise to a large or small value of the velocity of propagation of massless fields for a given multiverse? Thanks!

By Uncertainty Principle speed of a particle cannot be constant. then speed of a single photon not?

if speed of light were not 3*10 ^8 m/s and something else would it affect the reality ?

Homework Statement The problem I have been working with recently has been deriving the speed of light using maxwells equations, however in order to do this I must make two assumptions; there is no net charge or displacement currents in the space in which I am attemptin to derive the speed of...

Newton's law of gravitation cannot be compatible with relativity because the gravity from a massive object applies a force to all other masses infinitely fast. General relativity is supposed to correct this flaw by setting a speed limit on how fast the effect of gravity can reach a distant...

Good day all, This is my first post here, hope you all are able to help me out here. I am thinking about converting an old Suzuki GS500E from an internal combustion engine to an electric motor. At the moment I am having some difficulties with the physics side of things, I would like to...

Homework Statement A soccer ball is kicked with an initial horizontal velocity of 15m/s and an initial velocity of 16m/s. What's the speed of the ball 1 second after it was kicked? Homework Equations Initial velocity = sqrt([horiz. Velocity]^2 + [vertical Velocity]^2) Final velocity = initial...

Hi everyone, I often work on a SEM, a type of microscope which is based on electron acceleration between an electron source and the sample you are working on. For this reason and since a few weeks I was wondering how an electron (in term of speed) behaves in a constant and linear electric field...

I was playing a game of running (Need for Speed Underground) and was the second time that I thought how to determine the speed of the brain or the speed of the thought. I was running to more 200 km/h (you guys use mph, I'm from a country that uses km/h). And I crashing a lot with more 200 km/h...

Greg Bernhardt submitted a new PF Insights post Direct Echo-Based Measurement of the Speed of Sound Continue reading the Original PF Insights Post.

The speed of light from a moving source of light is usually recognized indirectly, based on various explanations of phenomena. The speed of light is fairly simple directly measurable on the basis of autonomous and separate measurements of the frequency and wavelength of the light. Is a similar...

Let us imagine a photon circling around a black hole, as the picture shows. The gravity of the black hole curves the movement path of the photon into the shape of a circle. From point 0, geometric points A and B appear simultaneously with the photon, each in its own direction. The points travel...

Homework Statement 15.1 The airspeed of the plane is 200m/s, directed north. If the wind speed is 30m/s in the direction shown, determine the ground speed and the course (angle θ) of the plane. Homework Equations The Attempt at a Solution Is it so far correct the above? More questions...

Good evening! The question states: 9. Electron in bound orbit about proton. Suppose that an electron moves in a circular orbit about a proton at a distance of 2 X l0^-8 cm. Consider the proton to be at rest. (a) Solve for the velocity of the electron by equating the centrifugal and...

Hi 1-)If an object's total velocity through space-time(four-velocity)is c, for example even we stand still we move with velocity c (through time) and if mass slows down time, can we say mass also increase our velocity in space? 2-) Is Four-velocity magnitude constant in General Relativity...

Imagine a car which has a speaker attached to the back. Speaker is blasting very high volume music towards the reverse direction of the car. Now the car starts accelerating and in a few seconds starts moving faster than the speed of sound. Will a listener be able to hear the sound now. Will...

Suppose for the sake of argument someone said the outward speed of light is infinite and the return speed is c/2, creating a two-way speed of c. Wouldn't this violate the conservation of momentum? p = E/c. That means on the way out, the momentum of light would be zero, but on the way back it...

what is the speed of Earth as it travels the cosmos,compared with the center of the universe.lets say the big bang starting point.?

Homework Statement A baseball has a terminal speed of 42 m/s in air (ρ = 1.2 kg/m^3). What would be its terminal speed in water (ρ = 1.0 x 10^3 kg/m^3)? A) 0.05 m/s B) 1.5 m/s C) 18 m/s D) 42 m/s E) 1200 m/s Homework Equations D=½Cρ*Av^2 where the magnitude of the drag force (D), relative...

What If the velocity of particle moving in a circular orbit has increased , would the particle be no longer in circular orbit or it would go in an orbit with bigger radius?

As I understand it, Newton considered the influence of gravity between two objects to be instantaneous. Now it would appear that gravity has a speed limit. If the Earth is influenced by the sun from where it was 8 minutes ago, how does the Earth keep up with a traveling sun? Does relativity...

Does anyone know the speed of light in dark matter?

I recently saw this question on a forum thread on The Guardian's website but was unable to follow it up. Question: Why is the speed of light what it is? Could it have been another velocity?

Hi all I have struggled with the assumptions that the speed of light is absolute and constant. I have some logic to this which is based on the common assumptions that light behaves both as a wave and a particle. It is also based on light having mass, the effects of heat and vacuum environments...

Homework Statement I have a question asking me to find the launch speed of a ball (mass 0.39kg) when released by a spring mechanism made of 2 springs each with force constant 25Nm^-2. they are pulled back 12 cm. the ball is initially at rest.Homework Equations [/B] v^2=u^2+2as f=ma f=kx...

Hello, I am on the search for papers, books, etc. on how one can measure the viscosity of viscous materials via the speed of sound. I've searched for a while now and haven't been able to find much on this topic. Any help is greatly appreciated.

If a car drives on the highway at a speed of 100 ft per seconds and a gun in the car shoots a bullet forward at the speed of 1000 ft per second the total speed of the bullet will be 1000 + 100 = 1100 ft per second. If a car travels at the speed of light when you turn on the head lights will...

Hello everyone, I'll go straight to the question. The gravitational time dilation is equal to tearth = tspace*sqrt(1 - rs/r), with rs = 2GM/c2. However, the formula for speed of light in gravitational field is equal to v = c(1 - rs/r). My intuition tells me that these two formulas must be the...

In discussion with my friend, we reached a conclusion that transformation formula of velosity v to another IFR moving V, i.e. v'=\frac{v+V}{1+vV/c^2} is valid even if v is hypothetical velocity,i,e, v=\frac{x_2-x_1}{t_2-t_1} v'=\frac{x'_2-x'_1}{t'_2-t'_1} where interval of ##(t_1,x_1)\rightarrow...

Are there any relationships between the speed of light and the virtual particles in the vacuum? I mean that, Can I call it as a medium of propagation of a light beam?

The way I have understood it is that dynamic torque involves angular acceleration, while static torque has zero angular acceleration: α =Δω/Δt = 0 But static torque still has centripetal acceleration with constant speed: ac = v2/r where v is linear velocity, and r is the radius Then F = mac...

As a neophyte when it comes to the relativity solutions I have been surfing the web. I came across something in Science Forums. <speculative link deleted> I have now become interested in what gravity does to light. My understanding of the post above is that the reference frame for light...

I have a somewhat hypothetical scenario that I've been thinking about lately. I have a pretty basic understanding of physics and the mathematics involved but i enjoy learning about astronomy and astrophysics. So the scenario is this, let's say an object such as a huge star or galaxy was to...

I decided to read up on the chapters we didn’t cover in first year Physics from my textbook, and decided to start with general relativity since it was in the same section of the textbook as the last topic we covered (that topic was physical optics - not lenses- photons and the double slit...

Homework Statement Homework EquationsThe Attempt at a Solution I don't understand which concept to apply in this question . The hint says to apply Bernoulli's equation and uses ∆P (excess pressure ) = (1/2) ρ v2 . This does give right answer . But I think this is wrong . We cannot apply...

Suppose we have an ultrasonic transmitter and an ultrasonic receiver, separated by some fixed distance ##d##. Both devices are attached to an oscilloscope. The transmitter generates ultrasonic waves at some frequency ##f## that we can change. The receiver is some piezoelectric that translates...

Hello, Wikipedia gave me prior hints as to how the speed of sound depends on viscosity but after searching on Google scholar and Google, I have yet to find any direct equations/findings that give a direct relationship of the speed of sound to the visocisty of fluids and solids outside of...

Using Newton's 2nd law F=ma, If you provide a constant force of 1mil Newtons then an object will accelerate at 100m/s. Using V = U + AT I can say that (speed of light) 299,792,458 = 0 + 100T thus T = 2997924.58 seconds or I can achieve speed of light in 35 days or so. Why is this not...

Homework Statement which one would be faster when reached the ground? Homework EquationsThe Attempt at a Solution conservation of energy Pe=Ke mgh=1/2mV^2 for 2-)m*g*cosa*(h/cosa)=1/2*m*V^2 -- V= sqrt(2*g*h) for 1-) V=sqrt(2*g*h) so V1=V2

Just wondering how a photon reacts when it is affected by gravity of an object in space like a star. Does the gravity actually bend the light/photons? Say you have a series of photons in a perfect line, all travelling, well, at the speed of light toward a massive object(x). The photons in the...

mass of air X velocity = mass of man x gravity (10000)x(v)=60x10 velocity=600/10000 how come velocity is so less? I am still in school so forgive me if my calculations look stupid.

If you heat something by radiation, its temperature increases, which means there is an increase of the average velocity of the atoms the "something" is made of. Another thing which happens when radiation hit the object, is that its atoms can "absorb" photons, as electrons go to higher energy...

I don't know what's the appropriate title for my question but here it is: What's the reference we consider to measure the speed with respect to when we say that as the speed of a moving object approaches the speed of light the time becomes slower in the frame of this moving object.

Any one please tell,all experiment attempt to find speed of light

I n ordinary weighing scale, in left pan, there is spiral shaped coil (like that mosquito coil) or any long shaped rod. Middle point of this coil is touching the left pan. Let mass of this coil be W1. Second body of mass W2 is attached to other end of this coil. So the left pan is experiencing...