Speed Definition and 999 Threads

Hello forums, I'm kind of new nice to meet you guys and girls, Could someone please explain this to me? D=S * TTherefore Distance = Speed of light * TimeAnd then Distance = Speed of light + 7 * TimeWhat is Distance and what is time?

I am trying to get a better understanding about the constancy of the speed of light which is a well-established axiom of current day physics. for the start i want to understand how it is experimentally established and how these results are interpreted. My difficulty here is that this seems to be...

Homework Statement A disk [m=0.1 Kg; R=0.1 m] rotates about its center of mass [w=40 rad/s], on a smooth floor. A bar [m=0.1 Kg; lenght=R=0.1 m] moves on the floor with a speed Vb=4 m/s. At one point, the bar hits disk's edge in an inelastic collision, and they start rotating together. A)[Fixed...

Hi people! May be this could be an historical question. Before Einstein, it is suppoused that speed of light in ether is always the same, I´m right? I mean, if observer O is at rest respect ether and observer O´ is moving respect ether and O´ send a photon to O, the speed at which that photon...

How to calculate the speed of cross flow water turbine? Help, I'm struggling on our machine design.

I have conducted an experiment that measures the velocity of an object that is moving on a flat surface. The object rolls on four fixed caster wheels. The wheels are made of some kind of rigid material. Maybe nylon, maybe hard rubber. The total mass of the object, including the wheels, is...

If you were to travel alongside a train, as fast the train, to you the train would seem stationary. I read that if you were to travel along a photon of light, as fast as the speed of light, that photon would not seem stationary. Is this true? If so, why?

Hello Dear Ones. 1. How Scientists exactly calculated movement speed of solar system ? thank you very much.

Hi, first of all sorry... I know (close to) absolutely nothing about physics except from what I remember from school a looong time ago... :-). So, my question might sound a bit silly here. But thanks a lot for taking you time already! Homework Statement In retail business there is some...

I saw on a web page a video of tiny Agnes Scott College vs Princeton University from 1966 on GE College Bowl.Agnes Scott won (!), but one of the questions that both schools got wrong was asked by the moderator: The speed of sound in air is about 1,100 feet/sec. The speed of sound in steel is...

Homework Statement A stunt motorcyclist has to jump across a river 7.0 m wide from a ramp on one side with incline of 10 degrees. (a) What minimum speed the motorcycle must have to successfully land on the opposite side of the river? (b) How long will the motorcyclist be in the air? (Assume...

Homework Statement The moving proton hits the second proton, which we consider to be stationary. In the moment of central strike gap between the protons is 10(-13)m. What was the initial speed of the moving proton? Proton mass is 1.67*10(-27)kg and charge 1.6*10(-19) C. Homework Equations...

Homework Statement A solid uniform disk of mass 21.0 kg and radius 85.0 cm is at rest flat on a frictionless surface A string is wrapped around the rim of the disk and a constant force of 35.0 N is applied to the string. The string does not slip on the rim. 1- When the disk has moved a...

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...