Speed Definition and 999 Threads

Homework Statement:: project not homework Relevant Equations:: vectors Hi,I am trying to determine the maximum linear velocity of a propeller tip when subject to flowing water with velocity ##\vec V##. For simplicity, I will assume that rotational inertial is negligible. The drawing below...

Hello how are you :D I have some problems with my code, which is to control the speed of a DC motor by pwm with the pic16f84A. I already have the combinations and the diagram of the signals, but I still need to implement the part in bold. How would the delays be implemented so that they have...

Since the brick has fallen 30m and the acceleration of gravity is 10m/s^2 the brick would have fallen 3 seconds speed of brick would then be 30/3 leaving the answer at 10m/s?I am new to physics and this question has left me stumped

This is my first post so I apologize if i am in error anywhere. I recently had a thought that I have had trouble confirming. Based on the following assumptions. 1.) As you accelerate an object near the speed of light it’s mass increases exponentially. 2.) Mass warps space time. 3.) Spacetime...

I have an answer to a partial differential equation. I have the equation coded as followed. I am trying to get this wave to propagate back after it hits a given z value. Can anyone help me figure out the direction in this equation...

Hello, Is there a mirror that will reflect light in parallel trajectories ? If yes, is the reflected light in sync, and will all beams hit a flat surface simultaneously ? Thank you

https://ibb.co/jG6n0jZ The 15 is fine as this is clearly his overall magnitude but then v2 is equated to the horizontal velocity rather than the magnitude.

The question constantly arises how the speed of light is measured and what does it mean that the speed is constant, including at remote points for the observer, including at points beyond the local frame of reference, as you understand it in general relativity (GR). First of all, it should be...

The solution on my textbook is 13000m/s toward Earth as the light is blue-shifted I'm able to calculate the magnitude of velocity (13000m/s), but i don't understand why thus is blue-shifted? Since in the lab, the light's wavelength observed is slightly higher than light from Ursa Majoris. So my...

My textbook is deriving wave speed on a string under tension with confusing thetas. It assumes ##\tan \theta_1 = \frac{-F_1}{F_T}## and ##\tan \theta_2 = \frac{F_2}{F_T}## which confuses me. I know for sure theta is the angle due to the position of y and x, ##\tan \theta = \frac{y}{x}##, but I...

The idea is to have 2 clocks at position A and B. The clocks are synchronized by sending a light pulse from position S over 2 equal distances x. The receiver is at position R at a distance y rectangular to the direction AB and exactly in the middle between A and B and right below S. for proofing...

I have no idea how to go about this. Any help would be appreciated thanks :) Edit: I converted the 1.5 rev/s to rad/s = 9.4 rad/s

First off: I'm currently working on an RC car heavily focused on aerodynamics for a Project I'd like to add to my Uni application. I've created a model, ran it through CFD and came up with some numbers. Now I'd love to plot out an equation that displays either speed or acceleration in dependence...

Been thinking about this since I was 12. Suppose you had a 1 lightyear long pole, and on the other end was a button 1 inch away that activates a light. The light is powerful enough for you to see it 1 lightyear away. You push the pole 1 inch forward. How long does it take for the light to reach...

Please bear with me I am trying to get a grip with underlying principles. Starting to try and understand Einstein’s second postulate and distinguish that the speed of light is independent of the speed of the source – v - of objects, other than light with travel initiated independent of the...

We need to find each variable. ##I## is already given to us as 8 amps. The charge of an electron is 1.6 x 10^-19 coulombs. The cross sectional area will just be ##\pi(1.2∗10^−3)^2## m^2. Now we need to find the free electron density. We are given the density of of copper and can use dimensional...

By chance, I have read a paper that left me in shambles. I would like you to help me figure out if it makes sense or not. I tried to follow Bridgman's logic, without a complete success. The extraordinary claim is that, if you start with a system consisting of a 1cm^3 copper cube where 2 faces...

Assume that we have a 1.5 km x 100 cm^2 long straight pipe, totally inelastic and full of water. From time t = 0, a pressure of 300 000 Pa is continuously applied to the water with a piston at one extremity. This correspond to a force of 30 000 N on the pipe cross section in the direction of the...

I assumed since both pass the points they must have the same speed at both instances, so the average speed would be 15 and the speed when passing the object should be 30, since the equation of average speed.

If you're in a relativistic starship, approaching the speed of light, then if you get too close to it, do you end up becoming a black hole? Relativistic length decreases as you get closer to light speed. Relativistic mass increases as you do the same. Will your relativistic mass and relativistic...

First of all, I'm new to the forum, and rather uneducated, so I apologize this is likely in the wrong section. I've recently (like last night lol) started looking into freediving. I haven't taken any classes or anything yet, so all of this might be common and answered there. However, one of...

A station is orbiting a planet at a distance R1, a moon is orbiting the planet at distance R2 with the period T. The planet itself has a radius rp and a mass mp. We know that when an object adds its velocity at a point in the orbit, the height of the opposite orbit will increase. Determine the...

One of the reasons to suggest that light might be bent by gravity is the assumption that light is behaving as the other objects that bend their trajectories by gravity. On a similar ground, we could suggest that as the objects are experiencing Gravity Assist, then the light could be also...

I understand the relativistic effects at high speeds, what accounts for the constant speed of light at low speeds? Example... If I travel towards a beam of light at 25 MPH, I will still measure the light as traveling towards me at the speed of light and not the speed of light plus 25 MPH.

Good evening all, I had a question on how the standard for the meter is defined. A simple Google search tells us that since 1983, the meter has been internationally defined as the length of the path traveled by light in vacuum during a time interval of 1 / 299, 792, 458 of a second. Many other...

I assume the system starts from rest so the total initial momentum is zero. Let: M = mass of trolley + cylinder m = initial mass of oxygen Δm = mass of ejected oxygen u = speed of ejected oxygen Conservation of momentum: 0 = (M + m - Δm) . vmax - u . Δm 1) Is my equation correct? 2) I...

We know that as speed increases, time slows, and at the speed of light time apparently ceases. Imagine a hypothetical hitch-hiker sitting on a photon and speeding through the universe at -- well, the speed of light. If time has stopped for him (her?), what is his experience of his journey? Are...

I may be way off, but at some point in the past I understand there was super expansion where the universe expanded faster than the speed of light. If matter expanded with it it's an example of matter in separate areas moving apart faster than the speed of light. If it didn't the universe has...

Being a neophyte to physics, I try to visualize a light cone as it travels about. I try to put myself in it and use my car to talk of it. When I ride in my my car, I note that when I corner, one wheel will speed up as compared to the other side. A light cone does the same, and given that the...

As the summary indicates I want to control the speed of a petrol bike upto 60Kmph, so that it does not go beyond that. Now my questions are can it be controlled electrically, most probably I may want to control the throttle, but how to do it? What all sensors I may require one I can think of is...

I need help with this question how in the world is it A and C. In A everything is cancelling out so nothing is movingfand nothing moving to the right. In C its not moving to the right. Isnt it suppose to be D since sits going right constant to 20N.

Recently I have seen a number of General Relativity visualisations that show spacetime flowing towards any mass, similar to water flowing into a sink hole. ScienceClic's video is an example. That model is also used in the "waterfall model" to explain the event horizon of a black hole, as the...

I think infinite speed is unimaginable. If something is moving at infinite speed, we can't find it at all because it has moved to infinity. Furthermore, when the maximum speed is limited, a reasonable inference should be that observers in different reference frames should find the same one speed...

The question is of what does it depend on? We take it for a constant still how do we know that its the exactly the same as in a vacuum in a center or closer to the center of our galaxy for example. Why is the number what it is?

Hi guys, thanks for helping me! I am working on a home project that includes a privacy shade for my backyard. I have a 6'x15' vertical shade attached to two portable posts that are held up right by four legs ("X" shaped footprint). the surface footprint of the legs covers an area of 46"x70". I...

If light goes from air through glass, the reason the light bends is because I'm told that the light travels slower inside the glass. If I change my observer reference to inside the glass, the speed of light inside the medium it look like light is still traveling at the speed of light? if so, the...

I understand that it is a system with two degrees of freedom. And I chose as generalized coordinates the two angles shown in the pic I posted. I am having troubles in finding the kinetic energy of this system, cause the book tells me that the kinetic energy is something different then what I...

I think when the speed of light was measured (and predicted from Maxwell's equations) that the assumption was made that this speed was a cosmic speed limit Suppose that the cosmic speed limit was higher than c (not infinite) and that perhaps another form of radiation traveled at that speed...

Assuming that the observer moves along the direction of the light, does the speed of the observer's measuring instrument relative to the light source (which may be close to the speed of light) affect the brightness and/or power flux density measured by the observer? I'm not sure about this...

This is the problem, This is the textbook solution ; i think the textbook solution is not correct! My thought, ##S_{max}## will be given by $$\frac {dy}{dS}=0$$ $$\frac {dy}{dS}=\frac {-1}{400}S+\frac {1}{5}=0$$ $$S=80$$ It is maximum economy because ##y{''}<0##, i.e by use of the second...

Summary:: How fast does a human sized object(or a human) need move so I won’t be able to see it at all if it passes right next to me? Im trying to figure out something in regards to the Flash movies/Flash series but I’m super bad at calculations and math :( Do you think that mach 2...

Wawawawawawa! This was a tough one...:biggrin: Find the question below; Find my approach below: We have the following equations; 1. ##v=30-0.5t## 2. ##v=30-1.5t## Now the car changes its acceleration at some point i.e from ##-\frac{1}{2}## ##m/s^2## to ##-\frac{3}{2}## ##m/s^2## ... I...

There is lots of good information online about shock waves but I'm not finding what I want. If dynamite has a detonation rate of 6800 m/s does the shock wave travel at 6800 m/s? Is sound we hear 1 mile away the shock wave or the sound? What speed is an atom bomb shock wave? This large horn...

This is a textbook problem (Mechanics). Attached find the question and respective solution. This is fine with me, i like trying different ways of solving math related problems. My approach is as shown below. Using the graph sketch It follows that, ##s##= ##(35×12)##+##\frac...

If two people are holding a stick going from the Earth to the moon and the one on Earth pulls the stick, would the person on the moon feel it immediately? This question was answered on Quora and the answer given involves the speed of sound and claims that the person on the moon would not feel...

A, the train speed up?

Why we know that average speed of a single photon(in point particle view) equal the speed of EM wave?If average speed of a single photon smaller than c then there exist massive photons?

Is the accuracy of 10^-12 s achievable in measuring a neutrino's speed with current experiments? I have come across a number of papers stating the accuracy is in the order of nanoseconds. This is much lower accuracy than the measured speed of photons. I believe it is due to the difficulties in...

Let ##m_s = 0.05, m_{s_1} = 0.02, m_r = 0.12, L = 0.8.## be the masses of the two spheres, mass of the rod, and length of the rod. Then the work done by gravity when the rod reaches the vertical position is ##(m_s(L/2) - m_{s_2}(L/2))g## and the kinetic energy equals ##\frac{1}2 (\frac{1}{12}...