Speed Definition and 999 Threads

Homework Statement Rank the four objects (1kg solid sphere, 1kg hollow sphere, 2kg solid sphere and 1kg hoop) from fastest down the ramp to slowest. (Please see the attached screenshot for more details.) Homework Equations KE_rot = 1/2Iw^2 (where omega = w) The Attempt at a Solution Since we...

Homework Statement A ball of mass 0.075 is traveling horizontally with a speed of 2.20 m/s. It strikes a vertical wall and rebounds horizontally. Due to the collision with the wall, 20% of the ball's initial kinetic energy is dissipated. Show that the ball rebounds from the wall with a speed of...

I was curious, is the speed of light in a vacuum really constant to all observers no matter their speed or movement? Is it possible for someone to somehow see light travel slower?

1. The problem statement. A tennis ball of mass m moving horizontally with speed u strikes a vertical tennis racket. The ball bounces back with horizontal speed v. Homework Equations p = mv The Attempt at a Solution My answer was m(v-u), meaning the final momentum (mv) subtracted from the...

Homework Statement Serway Physics Chapter 2 19. A particle starts from rest and accelerates as shown in Figure P2.19. Determine (a) the particle's speed at t = 10.0s and at t = 20.0s and (b) the distance traveled in the first 20.0s Homework EquationsThe Attempt at a Solution I am...

Homework Statement I understand that if the change in impulse is 0.25, that because disc B is originally stationary the momentum disc B will have is equal to the impulse. My question is how do we do this in terms of change in momentum? Homework Equations ΔP = Pf - Pi P = mv The Attempt at a...

Using on-line formulas I show my modified 65 Mustang SIX-Cylinder can reach 122 MPH...don't think so! I understand outside forces act on a moving object, requiring more force to act against that force, to increase speed. I am old and not an engineer, so please excuse me if I use wrong terms, but...

Hey this Quadratic application question is giving me trouble. A jet flew from Tokyo to Bangkok, a distance of 4800km. On the return trip, the speed was decreased by 200km/h. If the difference in the times of the flights was 2 hours, what was the jets speed from Bangkok to Tokyo? Just need the...

Homework Statement If a midpoint of a guitar string executes simple harmonic motion following the form x(t)=Asin(wt+φ), and its angular frequency is ω = 2.76 × 103 s−1 and A=1.60mm. What is then its maximum speed of the string during this motion? And what is the maximum magnitude of the...

Homework Statement Please look at the attached screenshot. This problem is really confusing for me and I can't seem to make much sense out of it. Homework Equations Ei = Ef The Attempt at a Solution As you can see, I did get (a). (The other checkmarks, I guessed — there were only two...

I tried to calculted the rotating speed fro a proton from the clasical point of view by using its magnetic moment and the moment of a rotating sphere uniformly charged as example here: https://ocw.mit.edu/courses/physics/8-07-electromagnetism-ii-fall-2012/exams/MIT8_07F12_quizsol2.pdf It is said...

Hi. I am having trouble finding the speed at which the grs moving across jupiter. I have a problem that is asking me to calculate the speed but my number seems wrong. I've calculated about 15 m/s but i don't believe that is correct. i just want to check my answer. thanks.

Homework Statement This is not my homework question, I was asked to help with it, but I've been out of the engineering field for many years now. Here's the question: Starting from rest, a 2500 kg helicopter accelerates straight up at a constant 1.7 m/s2. What is the helicopter's height at the...

Homework Statement We have a plane which lift area is A=500 m2 and weight of plane is m= 540 000 kg. That the plane can stay in air the pressure difference between top and bottom of the lifts have to be: B>G --> Δp= (m*g)/A = 10 594.8 Pa. Homework Equations Bernoulli equation The Attempt at...

Homework Statement Photons incident upon free electrons that are essen- tially at rest are scattered by the electrons. As a consequence, the electrons gain kinetic energy. How do the frequency and speed of the photons present after the scattering compare to those present before the scattering...

Homework Statement True statements about Jupiter as it moves in its elliptical orbit around the Sun include which o the following? I. It has its greatest speed when closest to the Sun. II. It has its greatest potential energy when farthest from the Sun. III. The magnitude of its...

Homework Statement If an object moves in a circular path with a speed that increases at a constant rate, which of the following can be concluded? (A) The radial component of the force acting on the object is zero. (B) The net force acting on the object is zero. (C) The net force acting on...

Homework Statement An object with mass 100 kg moved in outer space. When it was at location < 9,-24,-4 > its speed was 3.5 m/s. A single constant force < 250,400,-170 > N acted on the object while the object moved from location < 9,-24,-4 > m to location < 15,-17,-8 > m. Then a different single...

Homework Statement A car has a mass of 1500kg. If the driver applies the breaks, the maximum amount of friction force that can be applies without skidding is 7000N. If the car is traveling at 25m/s, what is the shortest distance the car can stop safely? Homework Equations I'm assuming it has...

Homework Statement A plank of wood sits on top of two rollers with radius of 44.4 cm. The plank is pulled forward so it moves at a constant acceleration of 2.24 m/s^2, starting from rest, and the rollers roll without slipping along the ground and in contact with the plank. What is the...

Homework Statement In the file below. Homework Equations Speed= total distance over total time. Acceleration = change of speed over time The Attempt at a Solution [/B] I tought it is just E because of the first rule above. But then I doubt my answer since it moved with constant acceleration...

I keep hearing that the relative speed of light remains constant because time and lengths change with speed, what I believe is called the Lorentz factor. At slow speeds the Lorentz factor is extremely small, so what do people believe accounts for the rest of the change? If I travel...

Imagine I had a ruler 1 Planck length long, I then send it on a rocket close to the speed of light, does its length contract? It seems to my simple intuition, relativity would say yes and Qm would say no. Is there a simple solution to this ?

The Lorentz factor shows how fast one frame will judge speeds in another frame to be taking into account the relative motion between the two frames. The speed of light is a factor in the Lorentz factor but I have heard that this is not because the speed of light is fundamental to it. So...

Hello, I'm going to build a solar-powered go-kart. To determine the sprocket that I want to use I need a formula to calculate the top speed which also considers vehicle weight and other resistance forces. All the formulas I found just used sprocket tooth and rpm to calculate top speed but of...

I think it would be great if cars software could historize data such as speed, using turn signals, etc which can be used in court to prove/disprove if someone was in fact speeding or didn’t use their turn signal. Why haven’t companies moved this way yet?

Homework Statement Two cars are facing each other on a long straight airport runway. They are initially separated by a distance of 1 km. Car A begins to accelerate towards the other car at a uniform 0.5 ms^-2. Ten seconds later car B begins to move towards the other car with a uniform...

Homework Statement In the attached file. Homework Equations No equations needed. The Attempt at a Solution I answered it B. Not sure,though. If it is a thick rope the frequency decreses; therefore, the speed decreases.

Thank you everyone so much for all the explanations. However, I have another question here. I was reading Mr Tompkins and I understand that relativity of time exists because we have a certain absolute speed, beyond which nothing can travel. For our universe it is c. Are there any other proofs...

Hi, here I am again. This is also related to my previous threads. My question is: How do I calculate the power of generator in terms of speed(rpm) from a drive system (such as belt and chain drives)?

Homework Statement Train starts to travel in a straight line at increasing speeds. The first wagon passes next to me in 4 seconds. In how many seconds will the n-th wagon pass next to me? Homework Equations s= vo.t + 1/2at^2 v= vo + at The Attempt at a Solution First of all we didn't learn...

Homework Statement What is the speed of a proton that has been accelerated from rest through a potential difference of -1000V? Homework Equations ΔV=potential difference V=U/q Conservataion of energy U=qEd (d is distance the proton is moving...i think) The Attempt at a Solution Here is my...

Would there have been any relativistic effects if there was no ultimate speed?

I'm looking to calculate the ratio of a planetary gear train. With the ultimate goal of producing a spreadsheet/calculator to show the state of the gearbox (i.e. all shaft speeds) based on applied constraints. A gear set consists of Ring Gear, Planet Gear, Sun Gear. The sick diagram is the...

Homework Statement Plane is 300miles E of chicago and it leaves flying east at 500mph. Wind is blowing 50mph south. What is planes ground speed? Where is plane 0.6 hours later when pilot expects to land in cleveland? Homework EquationsThe Attempt at a Solution This is how I set it up I want...

I found the following blog post from a Ph.D., "The Riemann Hypothesis, explained", while trying to get up to speed with the Riemann Hypothesis. It is at, https://medium.com/@JorgenVeisdal/the-riemann-hypothesis-explained-fa01c1f75d3f It seemed well written as I could understand it. Delete or...

Homework Statement My question is, how do I show that speed is equal to group velocity? More information at https://imgur.com/a/m6FwNaG Homework Equations v_g = dw/dk The Attempt at a Solution Part a is substitution, part b uses v_g = dw/dk, part c is multiplication by h-bar, but I am stuck...

If the speed of light would change in the universe without any other natural constant changing, would all clocks be affected in the same way by this? This is implied by Einstein in this paper on page 368 http://myweb.rz.uni-augsburg.de/~eckern/adp/history/einstein-papers/1912_38_355-369.pdf...

I want to do an application that can connect to my Electric scooter (the kind you stand on) and can get a speed and engine temperature readings, i'm looking into a device i can attach to the wheel or a temperature gauge i can attach to the engine and get a reading from both of them something i...

Homework Statement Givens: An object with a mass of 2kg has a momentum of p=<-1,-2,3>. The first two questions asked for the magnitude of the momentum and the corresponding unit vector, which i found to be 3.74 and <-0.267,-0.535,0.802> respectively. The next question asks for the speed of the...

Is the speed of sound different through the same piece of metal when it is heated compared to when at ambient temperature?

Homework Statement I haven't taken a physics course yet, this is for independent study, so I don't have the strongest understanding quite yet. I was wondering if I could get some insight to this problem: Susie has planned a trip to a city 60 miles away. She wishes to have an average speed of...

Suppose a fluid passes from having laminar flow, to having a turbulent flow (like when passing after an object). How do fluid speed and fluid density change after that?

Homework Statement A girl throws a ball high into the air, and at its highest point it lands on a roof, where it gets stuck. You estimate the ball landed at a height of 21.0m from the ground and a horizontal distance of about 20.0m from where it was thrown. What is the speed that the girl threw...

Earth is moving through space. If I throw a ball straight up, it falls down to me and is not left behind. This is obviously because it already carries the momentum of Earth's movement. But if I fire a photon straight up, does it also carry a velocity component in direction of Earth's movement...

Homework Statement What is the speed of a photon with respect to another photon if: the two photons are going in the same direction. they are going in opposite direction? 2. The attempt at a solution I think the answer to the first question should be zero and to the second one be 2xC; C⇒speed...

I try to understand the following graphics with x-axis being the radius of a typical star : I would like to knwo if ##\delta c/c## (y-axis) represents the relative error between theoretical and experimental values or if it represents the fluctuations of speed of sound inside. If these are...

Homework Statement I tried to understand the problem b) and c).[/B] Homework Equations Faraday's law: ∇xE = - ∂B/∂t emf ε = Bdv Force : F =ma, Lorenz's force F=q(vxB) ==> ma = IdB Power : power of battery = εI, mechanical power of the wire = Fv The Attempt at a Solution I think I solved...

From NASA page: The inner parts of the rings move around Saturn faster than the outer parts, all in accordance with Kepler’s third law for small objects revolving about a massive, larger one. They orbit the planet with periods ranging from 5.8 hours for the inner edge of the C ring, to 14.3...

How to calculate the speed of sprocket connected to the turbine shaft of a cross flow turbine if I only have these given parameters: Net Head, Volume Flow Rate, Specific Weight of Water and Efficiency of Cross Flow Turbine? Does the Cross Flow Turbine, Turbine Shaft and Speed of Sprocket have...