Speed Definition and 1000 Threads

Homework Statement Homework Equations U = (1/2)kx^2 T = 2 * π * (m/k)^ (1/2) The Attempt at a Solution [/B] I said that the angular velocity is w = (2 * π) / t And the equation for velocity would be: v(t) = -Aw * cos (w * t) However, I don't know how to relate this to the speed at...

Homework Statement We know the momentum of an electron, which is: 1,48*10^-21. Momentum is m*v (mass*speed) If we divide the momentum by the mass of the electron to find electron's speed, it'll give a value where v> 3*10^8 m/s. Since speed can't be above speed of light, we have to calculate...

Homework Statement Homework Equations W =ΔKE The Attempt at a Solution found work done by spring -1.3 =ΔKE -1.3 = KEFINAL - KEINITIAL -1.3 = .5(0.25)(VFINAL2) - .5(0.25)(VINITIAL2) Since v final is 0 since it stops momenteraly at the bottom of the spring -1.3 = - .5(0.25)(VINITIAL2)...

Homework Statement Special Relativity Question. Consider objects 1 and 2 moving in the lab frame; they both start at the origin, and #1 moves with a speed u and #2 moves with a speed v. They both move in straight lines, with an angle θ between their trajectories (again in the lab frame). What...

Homework Statement A ##5 ~kg## mass performs circular motion at the end of a light, inextensible string of length ##3~m##. If the speed of the mass is ##2 ~ms^{-1} ## when the string is horizontal, what is its speed at the bottom of the circle? (assume ##g=10~ms^{-1}##) (Ans: ##8~ms^{-1}##)...

Homework Statement [/B] A particle P1 moves with a constant velocity v along x-axis, starting from origin. Another particle P2 chases particle P1 with constant speed v, starting from the point (0, d). Both motion begin simultaneously. Find - 1. Initial acceleration of P2. 2. Ultimate...

Homework Statement Homework EquationsThe Attempt at a Solution I have placed the origin at the middle of the mirrors . This means object is at the origin . Now I am bit unsure about what the question means with 5th reflection .I am assuming that it means 5th image in either of the mirrors...

Homework Statement Calculate the speed of the block in SHM as it moves through equilibrium position. k= 45.08248265 N/m m of block = 0.505kg T = 0.665s Homework Equations w= the square root of (k/m) ? The Attempt at a Solution w = the square root of (45.08248265/0.505) = 9.448398958 =...

I am having a problem with understanding concepts related to the speed of a wave. Here are my thoughts laid out: 1) The speed of a wave is dependent only on the medium 2) When a wave crosses from a less dense medium into a more dense medium (or visa versa) the speed of the wave is always...

Consider a meter stick sliding along its length towards a hole which is a meter wide in the direction of motion. Suppose the meter stick moves with speed so that the gamma factor is 10. Then in the stick’s frame, the hole is 10cm and should be easy to cross. But in the hole’s frame, the stick...

Homework Statement P62 Sterling. #11 A new design for a car is to have a large disc like flywheel within the car storing kinetic energy. The flywheel has a mass of 370 kg witha radius of 0.5 meters and can rotate up to 200 revolutions a second. Assuming all of this store kinetic energy can be...

How fast would you have to go to reach a star 240 light years away in an 85-year human lifetime? Here, I know that I'm supposed to find $v$, but I'm having a hard time setting up my equation(s) in order to reach the final answer. :(

Hello. Galileo claimed that a body could not "by itself" change the state of rest or uniform rectilinear motion of its center of gravity. Newton clarified this with the notion of force and inertia. F = m.a. So let's follow a mass m. Either a closed container containing a gas. And one of the...

I've been told that when a photon of light is created it instantly achieves the speed of light without having to 'speed up". How is this possible?

Homework Statement You should shoot a basketball at the angle ##\theta## requiring minimum speed. Avoid line drives and rainbows. Shooting from (0, 0) with the basket at (a, b), minimize ##f(\theta)= 1/(a \sin (\theta) \cos (\theta) -b \cos^2 (\theta))##. (a) If b =0 you are level with the...

Special relativity requires any substance to be compressible. Indeed, if an item were made of a perfectly rigid substance, then move one end of it, and the other end must move at the same moment - the movement must be transmitted instantly, faster than light. Thus, the special relativity sets...

Homework Statement Gravitational force exerted on mass m is GMm/r^2 2. Relevant equations Orbital velocity at distance R from Earth = ##\sqrt gR## Escape velocity = ##\sqrt 2gR## gR = GM/R Fc = mV^2/R F =m.aThe Attempt at a Solution 1) express acceleration of gravity in terms of G, M , and R...

Hello, If the speed of light is the maximum speed limit in our universe, how was the big bang event possible because surely the expansion would have been constrained by the speed of light?

So an object unaffected by any gravity free floating in space has zero mass. Now could this object reach light speed. Or am I confused?

Homework Statement Cart travels with a mass of 100kg in the 25m/s in the X-Direction and then 20m/s in the Y-Direction. What is the impulse? Homework Equations I = m*change in velocity The Attempt at a Solution I = 100(20 (j) - 25(i)) I = (2000 (j) - 2500(j)) kg* m/s Is this correct?

Homework Statement The doorway in the previous question measures 1.06 m x 2.04 m, and the wind blows parallel to the wall surface at 3.89 m.s-1. Calculate the force pushing the curtains out of the doorway. The density of air is 1.29 kg.m-3. Known data: A = (1.06m)(2.04m) = 2.162 m^2 v(wind)...

I try to calculate the speed curve of a relativistic rocket driven by a 100% efficient engine with constant thrust, when traveling to a distant star. All equations I can find consider constant acceleration, which of course is not working, since the ships mass decreases when the fuel is used...

I understand that the centripetal force on an object of mass 'm' is (mv2)/r However, isn't this for an object going around in a circle? Suppose I have a curve (0.0033x2+−1.0038x+98.2331). What would be the fastest speed around this curve on the bounds x -> Please note that we would...

Homework Statement A metal rod can slide on a rail without any friction in the presence of uniform magnetic field of B=1T which is perpendicular to the plane of the paper.The distance between the tracks is d=0.1m and the resistance given is R=0.1 ohm.The resistance of the rail is negligible and...

Hello - I'm posting this here because of a discussion I got into on another forum following the recent death of Stephen Hawking. I should stress that I am by no stretch of the imagination a physicist (though I did do modules on special relativity and quantum mechanics as part of my maths degree...

What is wrong here. If I double speed drag will be 4 times higher. The engine needs to put out approximately 4 times more power. Energy consumption will be 4 time higher for a specific time period. However if it is a fixed distance I will arrive in half the time an the energy consumption will...

For physical experiment I have a project in which I have to measure the speed of sound in the air. 1. If I take an iron tube (inside is air) and a speaker, 2. put the speaker at the beginning of a tube, 3. speaker is connected to frequency generator (with which I can change frequencies)...

Homework Statement The kinetic energy of a 20N object is 5.00 x 10^2 J. What is the speed? Homework Equations Ek= 1/2 mv^2 and *i think* F=mg The Attempt at a Solution F=mg m=F/g m=20N/9.81 m/s^2 m= 2.038 kg Ek= 1/2 mv^2 v=sq. root 2Ek/m v=sq. root 2(5.00 x 10^2 J)/2.038 kg v= 490 m/sIs...

Homework Statement A Jet is heading due east: its nose points towards the east direction, but its trajectory on the ground deviates from the east direction due to a sideways component of the wind. The plane is also climbing at the rate of 100 km/h (height increase per unit time). If the plane's...

A rocket is in constant velocity. The velocity of the rocket is 150Mm/s (or 0.5 of the speed light, or 150 million meters per second) relative to us (we as observer). We observe two lights, one moving in parallell with the rocket, another is moving in the opposite direction. Below I have made...

Does the speed of light change in different substances, or does it seem to change because it gets absorbed and emitted by all the particles?

Homework Statement y(x,t)=0.8/{(4x+5t)^2+5 }represents a moving pulse,where x and y are in metre and tin second.Then choose the options. (a)Pulse is moving in positive X axis (b)In 2 secs,it will travel a displacement of 2.5m (c)It's maximum displacement is 0.16m (d)It is a symmetric pulse...

First I want to say that I plan to study mathematics and physics in college, so I do not know how a lot of things work exactly since I have not really had a formal physics class. I was wondering if all light moves the same speed, or can some light move faster than other lights for certain...

c² = (n/m) ∂²U/∂n² where U = vacuum energy density as a function of the quasiparticle density n = quasiparticle number density m = bare mass of quasiparticle Is there a book, article where this formula is explained? Thank you.

The two pulleys connected by a belt have a radii of 15 cm and 8 cm. The larger pulley rotates 24 times in 36 seconds. a. Find the angular velocity of the small pulley in radians per second. b. Find the linear velocity of a point on the belt that connects the two pulleys in centimeters per second.

Homework Statement Consider a bumpy road in which each hump has the shape ##y=\cosh(a)-\cosh(x)## for ##-a\leq x \leq a## where ##y'(a)=-1## so ##a=arcsinh(1)## L=2 ##(x_p(t), y_p(t)) = (t, \cosh(a)-\cosh(t))## ##(x_q(t), y_q(t)) = (t, \cosh(a))## We place the square wheel onto the bumpy...

Respected physicists and members (I am not a physicist) I have a little doubt that i want to clarify. If I am sitting in a stationary train, having a ball in my hand, the ball will remain stationary relative to my hand and plateform. Now if the train starts moving, again the ball is stationary...

Homework Statement A floral clock in Japan has a radius of 15.5 m. If you ride a bike around the clock, making 16.0 revolutions in 4.50 min, what is your average angular speed? Homework Equations ω = velocity/radius ; 1 rev=2*pi rad The Attempt at a Solution (16 rev*2*pi rad)/270 secs = 0.372...

Homework Statement A motorcycle goes up a hill at a constant speed of 10 miles per hour and comes down at the speed of 25 miles per hour what is the average speed for the entire duration? Homework Equations Vavg =(vf-vi)÷2 The Attempt at a Solution It seems very straightforward that this...

Homework Statement At point A in the flow of a compressible fluid, the flow speed is 100 m s−1 and the Mach number of the flow is 0.6. Find (i) the maximum possible flow speed on the streamline through A, and (ii) the flow speed at a point where the pressure has fallen to half its value at...

Is it possible that the speed of light exists because we cannot move faster than our particles? I.e. the speed of electrons that create the electromagnetic force that hold matter together.

Hello, I came to this site, with a question in mind. The speed of light. Nothing travels faster than the speed of light. This is a phrase, most of us are familiar with, to some extent. The word "Nothing" has two syllables, "No" & "Thing". There is no thing, that can, travel faster than the...

I'm thinking about flying off in a spaceship that travels half the speed of light so I can, in effect, travel into the future, since everyone stuck on Earth will be going relatively slow and aging relatively faster than me. But my concern is that I don't know which way to go. Right now the...

In Einstein's famous equation, why did he use the speed of light squared? Why not some other constant?

What would happen if a car is driving down a highway at 80Mph and one of the doors is fully opened. Will it make a big change and make it slow down or start turning?

A torsional pendulum made by suspending a horizontal uniform metal disk by a wire from its center. If the disk is rotated and then released, it willexecute simple (angular) harmonic motion. Suppose at t seconds the angular displacement of \theta radians from the initial position is given by the...

I have been having a conversation with a few friends, and we have been discussing the speed of stars in a galaxy base of the wave lengths. We have 2 stars measuring wave lengths 494.6nm and 494.2nm. At rest the wavelength is 486.1nm. From this we managed to deduce that the speed of both stars...

Hello. I read an article about aerodynamics. http://www.cyclist.co.uk/in-depth/2873/fat-v-skinny-who-goes-downhill-faster I'm a little bit confused with this statement regarding mass, drag, and velocity: "When you increase the mass the speed increases by cubic function, whereas if you...

For the critical speed of the shaft, should I include the weight of the members mounted on the shaft (gears, pulleys, etc.) with the forces acting on it?

Hello people, I have 3 questions related to the mean speed of electrons in a period potential /lattice. I've read Ashcroft and Mermin's page 139 as well as the Apendix E. From what I understood, if one applies the momentum operator on the wavefunction of a Bloch electron, one doesn't get a...