Accelerating Definition and 669 Threads

Lets say you have two perfectly reflective parallel mirrors in a frictionless vacuum. You fire off a beam of light between them, so that it bounces between them continuously. Do they continuously accelerate away from each other due to radiation pressure? I think the answer must be no, but I...

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > I have read every post I've found on here about this subject, but for some reason the answer is elusive - I suspect due to an issue with units. Here's the problem. vInitial = 0 meters / sec Mass...

Suppose I am stationary in space (no velocity). My body is straight. There is a stationary ball right beside me (also no velocity). Then an accelerating platform hit my feet and the ball from under. Now the ball and I are in contact with the platform constantly and accelerate at the same rate as...

I've seen this question come up before and I have an intuitive explanation: In circular motion, the object is being pulled toward the center, so some of its velocity is being imparted from its tangential path toward the center. If its position with reference towards the center is changing...

Homework Statement An object starts from rest with an acceleration of 2.0 m/s2 for 3.0 seconds. It then reduces its acceleration to 1.0 m/s2 for 5.0 additional seconds. The total distance covered is Homework Equations The Attempt at a Solution I've tried using the formula of velocity =...

An accelerating charge radiates light. But in its own frame of reference it is stationary. So it does not emit light. How is this explained? Extreme Example: A charge inside an elevator is falling in a gravitational field. The elevator is lined with a light sensitive sensor that triggers a...

Homework Statement Two point charges q1 and q2 are held in place 4.50 cm apart. Another point charge -2.00μC of mass 6.00g is initially located 3.00 cm from each of these charges and released from rest. You observe that the initial acceleration of -2.00μC is 354m/s^2 upward, parallel to the...

Homework Statement Suppose that you are standing on a train accelerating at 0.16g. What minimum coefficient of static friction must exist between your feet and the floor if you are not to slide?Homework Equations F=ma The Attempt at a Solution

I attempted to find a formula relating the velocity of an object released from infinity moving towards a mass ##M##to the distance ##r## from ##M##. According to Newton's law of gravity, ##a=\frac{GM}{r^2}##. Since ##a=v \frac{dv}{dr}## , ## \int a dr = \int v dv = \frac{v^2}{2} + k##. Since...

Homework Statement The question is: A simple pendulum is mounted in an elevator. What happens to the period of the pendulum (does it increase, decrease, or remain the same) if the elevator (a) accelerates upward at 5 m/s/s (b) moves upward at a steady 5 m/s (c) accelerates downward at 5 m/s/s...

Guys, I'm looking for some checking of my own understanding about the EM waves given off by accelerated particles. Specifically, is this radiation only due to disturbances in a previously static electric field...therefore we are viewing this disturbance as a wave? Or, is there more to the...

Ok. I'm trying to get this straight in my mind. I am familiar with Einstein's equivalence of acceleration and gravity. But what I am trying to figure out is: who exactly is accelerating? If someone is falling to the Earth and I am looking at his pitiful circumstance, he is clearly -...

I have a question which has intrigued me for quite some time. If the electrons are accelerated using a potential difference in a cathode ray tube, the electrons should get accelerated till the time they reach the anode only. Once they cross over (ie. move to the other side of the anode), they...

I always see that a ball moving in a constant speed collide with another ball is common conservation of momentum problems. Obviously, I know that the momentum is mass*velocity But, what if the ball accelerates and collides with another ball ? I think I can't use mass*velocity for the momentum...

[Mentor's note: no template because this thread was moved into the homework forum after it had already attracted several useful replies] [Mentor's note: Thread title changed to reflect question content] The question is: An electron is a subatomic particle (m = 9.11 10-31 kg) that is subject to...

We know that when a rigid frame, say a rocket undergoes constant proper acceleration, its worldline is hyperbolic. The equation is given by: x^2 - c^2t^2 = \left( \frac{c^2}{a_0} \right)^2 Suppose P is such a worldline and worldine can also be written as: I understand how these are...

Hi there! I have a problem to find an equation of r(t), which will help me to describe motion of blue dot. I have seen many cases where there is a linear motion and you can write φ=ωt , r=V0t, but here there is an acceleration. I think I can write φ=εt2/2, but what about r(t) ? I have tried...

Homework Statement A solid cylinder (I = 1/2 mr^2) is being pulled by a force applied at 40 degrees above the horizontal to the axle and directed through the center of the roller. Roller moves across a flat, horizontal surface. Cylinder has radius of 0.60 m, and mass of 250 kg. Assume roller...

Homework Statement I am trying to answer the question: "An electron is accelerated in an evacuated chamber. Sketch lines that illustrate how the magnetic field produced by the electron will vary with time. "Homework Equations F=q(v x B) The Attempt at a Solution I cannot find a sketch of this...

Imagine if I were to apply a constant force, F, to a spring of length L, spring constant K, mass m, and uniform density. The force causes the spring to accelerate with acceleration a. For the sake of imagination, I will say I'm applying the force with my hand (which is pushing one end of the...

Homework Statement I need to accelerate a 0.2 gram projectile to 300 m/s within 80cm. How much force (N) do I need? Homework Equations E = F * S The Attempt at a Solution

Dear all, I would like to know if someone has experience with projectile accelerator (or mass accelerators). I am working in space research field and here is my question: I would like to know if we can find a system or a machine permitting to apply very high acceleration (like 10'000 g) at very...

Homework Statement Four blocks of masses 20kg, 30kg, 40kg, and 50kg are stacked on top of one another in an elevator in order of decreasing mass with the lightest mass on the top of the stack. The elevator moves downward with an acceleration of ##3.2m/s^2## . Find the contact force between the...

So I'm just asking a hypothetical question here, just looking for insight on something I'm thinking about really. Scientists are able to reach almost absolute zero by slowing the movement of particles with lasers. So I was thinking, is the inverse possible? If a laser was to strike incident...

Homework Statement A 900-kg car initially at rest rolls 50m down a hill inclined at an angle of 5.0^o. A 400-N effective friction force opposes its motion. (a) How fast is the car moving at the bottom? (b) What distance will it travel on a similar horizontal surface at the bottom of the hill...

Q. Two particles start simultaneously from the same point and move along two straight lines, one (particle A) with uniform velocity v and other (particle B) with a uniform acceleration a. If ##\alpha## is the angle between the lines of motion of two particles then the least value of relative...

Homework Statement In terms of the energy involved (using formulas provided), explain why accelerating a spacecraft to the speed of light is impossible. Homework Equations time, mass and length dilation formulas, and a few astrophysics formulas, E = Ek + mc2, projectile motion formulas The...

I tweeted neil Tyson, michio kaku and brian green the following: [link deleted by moderator] no responses yet, would like feedback - does the video make sense?

Homework Statement Sheldon moves a box of comic books to stuarts comic book store by attaching a rope to the box and pulling with a force of 90 N at an angle of 30. The box of comic books has a mass of 20 kg and the coefficient of kinetic friction between the bottom of the box and the sidewalk...

Hello all, I am calculating the loads on an unconstrained structure in space that is accelerating. There is a constant known force (T) being applied to it at one end (point A). The structure is a rocket with distributed mass but let's assume it is a uniform beam with constant density. I would...

I've been trying to find the latest, best guess, as to how long ago the universe's expansion began to accelerate (post-inflation). I've seen various estimates on websites from 5 billion to 8 billion years ago. Is there any kind of consensus in the community that studies these things as to a...

Homework Statement Car A is starting from rest and accelerating at 4.0 m/s^2, car B passes it, moving at a constant speed of 28 m/s. How long will it take car A to catch up with car B.Homework Equations d=Vot+1/at^2 The Attempt at a Solution Using the equation above, I used it for car A...

I know talking about faster than light speed travel is taboo on forums like this but the questions I have are these: Particle with Mass When an object travels faster and faster towards the speed of light and particles with mass are attracted to the object at a faster rate because of the...

Hello all, here is my problem: A car accelerates, starting from rest, with a speed that is given by: v(t)=vm(1-e-at) a) What is the top speed of the car? Explain why. b) How far does the car travel in time t? c) Suppose the car can accelerate from 0 to 60 mph in 2.9s, and has a...

My understanding is that a light beam will bend in an upward accelerating elevator. I told my uncle this. He responded that the velocity of the elevator cannot be added to the velocity of light since light's velocity always remains the same no matter the motion of the source or the observer...

Suppose a point charge is accelerating uniformly. It emits EM radiation. If an observer is co-moving with the point charge, the point charge remains at rest in his/her frame. So I guess it does not radiate relative to the co-moving frame. But someone told me that acceleration is absolute...

I’ve been thinking about Einstein’s gedankenexperiment (because I’m meta like that) regarding the sealed room on Earth, and the sealed room on a steadily accelerating rocket. And the result of this thought process is… I’m confused, probably because I do not correctly understand the parameters...

hey, I'm currently going through a mechanics course on edx.org . And part of last's week homework was this problem. well okay I don't know how to add images so I'm going to try my best to describe it. There is a platform has a mass of 200kg. From that platform a rope hangs( with tension TA...

Hello all, thank you for taking the time to read this post, i appologise if it is in the wrong section, as i am new to this. Why did people just invent Dark Energy to explain the accelerating expansion of the universe? I propose another idea that doesn't rely on fudging numbers to explain...

[b]1. in synchrotrons; as i understand, particles are only accelerated along the straight sections by an electric field established by electrodes. in my textbook, it says "a high frequency alternating voltage is applied between electrodes positioned around the ring which accelerates the charged...

According to Hubble's Law, the farther a galaxy is, the farther it is moving away. But do we take into account the fact that we are actually looking in the past? For example, there are two galaxies A and B at distance of 5 and 10 billion years respectively. Now, when we observe A we are...

Homework Statement There is a body of mass 500kg accelerating at 2.5ms^-2. It experiences a frictional force of 1000N. Homework Equations Resultant Force = ma The Attempt at a Solution Resultant Force = (500)(2.5)N = 1250N The body is moving forward with a net force of 1250N A...

Can we define a threshold velocity V for an object with mass(rest) M which the object at motion need to attain so that its center of mass accelerates faster than the Dimensional object?

Homework Statement A ball of mass m travels with speed v, hits a stationary ball with the same mass m and after collision they both move at speed v/2. From the point of view of the first ball the total momentum is -mv and after the collision it is 0. why isn't the law of conservation of...

Homework Statement A jet plane is cruising at 300 m/s when suddenly the pilot turns the engine up to full throttle. After traveling 4km, the jet is moving 400 m/s. What is the jet's acceleration? known: x0 = 0m, t0 = 0s, v0 = 300 m/s x1 = 4000m, t1 = ?, v1 = 400 m/s Homework...

I have an expected value probability problem. Unfortunately, I do not know enough about mathematics to determine if it is even remotely feasible to try to solve it. The best way to explain it is to disguise it as a physics problem: Imagine a race car on a never-ending straight track. Let's call...

Hi, I have a 1m long, 10mm ID vertical tube attached to a vacuum system. I have a known flow rate of the air down the tube which is used to calculate the air velocity. My question is if I then add micrometre sized particles (initially at rest) to the air stream what is their velocity at...

Homework Statement A 45 degree wedge is pushed along a table with constant acceleration A. A block of mass m slides without friction on the wedge. Find the block's acceleration. Gravity is directed down. Homework Equations Constraint Equation...

Homework Statement This is problem 2.11 from Kleppner and Kolenkow, 2nd edition. I have completed the problem but I'm not 100% sure I did it right and would like to check my understanding. A ##45## degree wedge is pushed along a table with constant acceleration ##A##. A block of mass ##m##...

Homework Statement An open rectangular tank contains water up to about half of its depth. This tank accelerates at a=2.20 m/s^{2} up a slope α (alpha), which causes the free water surface to form an angle θ (theta) with the original horizontal plane. What is the α angle of the slope?Homework...