Mechanics Definition and 999 Threads

For part 1, I got ## tan \alpha = 1/30 ## ##\alpha = 1.9^{\circ}## ##mgcos(1.9) = 10774N## I'm a little thrown off by the second part. Are we supposed to assume that in the absence of friction, F = N and then substitute F = ma to solve for this?

I recently started studying some quantum mechanics, so far I have been using online resources(like MIT OCW 8.04/8.05, and Tongs notes I think I have reached a stage where I understand the Schrodinger eqn and can solve it for various potentials(including for the H-atom) but I don't know anything...

I have sometimes seen the claim that one advantage of Lagrangian mechanics is that it works in any frame of reference, instead of like Newtonian mechanics which will hold only in the inertial frame of reference. However isn't this gain only at the sacrifice that the Lagrangian will need to take...

I am trying to find the launch angle ##\theta## using the relationship: ##\theta=\arctan(\frac{v_{y}}{v_{x}})## So, ignoring attenuation due to air resistance, we have a constant horizontal velocity: ##v_x = d_x/t = 95m/4.5s \approx 21 m/s## But what value do we use for ##v_y## which is not...

Hello (Perhaps this should be in physics, but perhaps it should be mechanical engineering (fluid mechanics). I attach a picture of water running down the street near my house. The street is a nearly constant 15 degree incline that goes on for about 1 kilo-meter with no speed bumps. The...

A lot of people say that Quantum Field theory (QFT) an Quantum Mechanics (QM) are equivalent. Yet, I've found others who dispute these claims. Among the counter-arguments (which I admittedly do not have the expertise to pick apart and check their validity in full) are the following: 1) While QFT...

Hello, I am doing some contact mechanics and I had an example in my Lecture notes about a simple thrust bearing with three balls where the bottom plate is stationary, the top plate rotates with angular velocity w, and the cage rotates with angular speed Ω. It says by inspection Ω =w/2 but I...

I just finished a new paper, A. Neumaier, Quantum mechanics via quantum tomography, arXiv:2110.05294. (later renamed to) A. Neumaier, Quantum tomography explains quantum mechanics, arXiv:2110.05294. Abstract: Starting from first principles inspired by quantum tomography rather than Born's...

Show that a point with acceleration given by: a=c*((dr/dt)×r)/|r|3 where c is a constant, moves on the surface of a cone. This is jut an example to illustrate my doubt. I don't know how to obtain the tracjectory given only the acceleration in this format. I realized that if i can show that...

I read about a proposal for storing potential energy by hoisting heavy weights that can be dropped when needed to generate electric power. So using the numbers from a hydraulic turbine from Hoover dam, how heavy would a hanging weight have to be to generate 178,000 horsepower as it descended...

Hello! Searching for above mentioned books for my Bsc studies. Like his style and the quantum and electro books were very well written(in my opinion) and easy to navigate through, also liked the pre-explained math tools i need for the book. Tried Goldstein and Taylor books on mechanics but they...

Take a simple case: A system is prepared in state ##\rho_i## at time ##t_0##, and a projective measurement is performed at time ##t_2## with an outcome ##b##. We can retrodict a projective measurement outcome ##a## at time ##t_1## where ##t_0<t_1<t_2##$$p(a|b) =...

for undergraduate students how to explain this?

An axiomatization of classical mechanics such as the one by McKinsey et al. (1) does not contain any reference to humans or experiments, and does not contain the magic (irony!) words of quantum mechanics, i.e. observables and measurements. (1) McKINSEY, J. C. C., et al. “Axiomatic Foundations...

I want to learn about the non holonomic case in lagrangian and Hamiltonian mechanics. I've seen that many people say that Goldstein 3rd ed is wrong there. Where should I go to learn it. My mathematics level is at the level Goldstein uses. Please help

Summary:: The problem solutions contain a lot of unjustified steps, making them pointless. I am trying to use Griffiths Introduction to Quantum Mechanics. He states that the wave function ##\psi## approaches 0 as x approaches infinity to make normalization work. I can accept that. But then I...

Collapse theories (like GRW) only need extremely few collapses to reproduce macroscopic observations, and actually must limit themselves to extremely view collapses to avoid being experimentally distinguishable with current technology from standard QM. Being too generous with world splitting in...

Is it easy to combine them or impossible? Is there a tension due to the non-locality found in Bohmian mechanics? Thank you!

I had two questions in the field of physics: We know that in quantum mechanics there is an electron in a certain distance from the distance to the nucleus as a cloud or a cover. But is motion for the cloud defined by the electron moving around the nucleus? And the main question is, can the...

Hello : i am reading now landau & lifshitz book on mechanics and i have small question : about L(v^2) notation it was not very clear in the book and i couldn't understand it correctly anyone can explain it or provide a link with explanation page (4 - 5) Best regards Hagop

Books that teaches classical mechanics through a discourse method ie asking interesting questions and answering them maybe a similar one to Understanding Basic Chemistry Through Problem Solving: The Learner's Approach Book by Jeanne Tan and Kim Seng Chan. Not exactly asking numerical questions...

Hello! If I place a particle with more energy levels (of the order of kT) in a well defined state, in a thermal bath at temperature T, how will the blackbody radiation affect the internal state of the particle i.e. will the distribution be classical or QM? Basically, if I prepare that particle...

Robert Lawrence Kuhn: It seems that special relativity suggests time is like gravity and electromagnetism, not built into the absolute fabric of reality like logic and causation. David J Gross: Yes, time is dynamical. The phenomena are dynamical and are labeled by what we call time. Including...

I'm trying to solve the Goldstein classical mechanics exercises 1.7. The problem is to prove: $$\frac{\partial \dot T}{\partial \dot q} - 2\frac{\partial T}{\partial q} = Q$$ Below is my progress, and I got stuck at one of the step. Now since we have langrange equation: $$\frac{d}{dt}...

If a hypothetical spacecraft could keep station at the 2nd focus of Earth's orbit, what useful observations could be made? Each minute sees a new solar triangle Earth Sun Craft (ESC). Swept area remains constant, as should length SC, and length CE + ES. With the Sun as our point source...

I read somewhere that Morse originally applied his theory to the calculus of variations. I'm wondering, is this application useful in physics and mechanics, like maybe it sheds light on lagrangian mechanics? Does anyone know?

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v_g+v_e=15/t_1 v_g-v_e=10/t_2 v_g=s/(t_1-t_2) But there are too many unknowns. What am I missing?

So initially I thought quantum mechanics was deterministic in the equations but was probabilistic in measurement. I’m aware of bell’s inequality which rules out hidden variables unless you assume super determinism. But recently I’ve come across something called decoherence and some people have...

Good day, I performed relatively well(A-) in the first course of my sophomore mechanics class, but I don't feel as if I've sufficiently mastered the material to perform well in the 2nd course in the sequence, and of course, the principles of Lagrangian and Hamiltonian mechanics, simple harmonic...

A hockey ball of mass 0.2kg is hit so that its initial speed is 8 m/s. The ball travels in a horizontal straight line with acceleration given by a= - 0.5- kt where t is the time in seconds measured from when the ball was hit. After 2s the ball has traveled 41/3 m. It is then intercepted by a...

Hello everyone. I am studying physics as a self-study and would like advice on the next topics to study. So far I have been studying: -calculus, linear algebra and basic physics -classical mechanics (from Goldstein's textbook) -classical electrodynamics and special relativity (from Griffiths...

Hello everyone, I am new here. I am studying physics as a self-taught student. I have been studying classical Lagrangian and Hamiltonian mechanics from Goldstein's book and have read that there is an additional formulation of classical mechanics in Hilbert spaces. Is it worth studying? Do you...

intermolecular distance means distance between particles. So, I imagine a sphere. $$\frac{4}{3} \pi d^3 = \frac{V}{N}$$ However, Griffitfhs pictures a box instead, where $$d^3 = \frac{V}{N}$$ And the difference between both models is a factor of ##(4\pi/3)^{2/5} \approx 1.8##, which is...

Two particles A and B are attached to the ends of a light inextensible string, which passes over a smooth pulley. Particle A has mass 8 kg and particle B has mass 5kg. Both the particles are held 1.2m above the ground. The system is released from rest and the particles move vertically. a) when...

Two particles A and B are attached to the ends of a light inextensible string, which passes over a smooth pulley. Particle A has mass 8 kg and particle B has mass 5kg. Both the particles are held 1.2m above the ground. The system is released from rest and the particles move vertically. a) when...

Knowing that ##F(x)=-\mathrm{d}V(x)/\mathrm{d}x##, I found that ##F(x)=-2.4x^3+1.35x^2+8x-3##. But it was the only thing I could find. How can I analyze what will be the type of movement with the information presented by the question statement?

It's the second question. Limiting equilibrium by a force of 5N means even friction is acting in the same direction. I don't understand how to calculate. Pls help

Iam not able to get the ans for q(a) which is 6.5 m/s I don't understand how to calculate (b)

A woman on a sledge moves in a straight line across horizontal ice. Her initial velocity is 2 m/s. Throughout the journey her acceleration is given by a= -0.01t m/s^2, where t is the time from the start in seconds. Find the distance that she travels before coming to rest. Iam getting the ans...

A goods train starts from rest at point A and moves along a straight track. The train moves with acceleration a m/s^2 at time t s, given by a=0.1t^2(6-t) for 0<t<6. It then moves at constant velocity for 6<t<156 before decelerating uniformly to stop at point B at t=165. Calculate the distance...

A particle starts at the origin and moves along the X- axis. The acceleration of the particle in the direction of the positive x-axis is a= 6t-c for some constant c. The particle is initially stationary and it is stationary again when it is at the point with x coordinate = -4. Find the value of...

I don't understand q(e) . Am I not supposed to calculate the distance between the interval 0 to 2? The textbook ans only shows the interval between 0 and 22. Should I calculate the distance taming only the second equation of velocity?

A particle moves in a straight line. The velocity of the particle, v m/s, at time t s is given by v= -t^3+9t m/s for 0<t<5 a) Find the displacement of the particle from its original position, when t=5s I got the ans for this by integration and limits 5 and 0 =- 43.8 b) work out the distance...

I calculated q(a)=1s q(b)=7cm I don't understand q(c)

S for 0 to 2s = 20m From 2s to 2.5s, I integrated v with limits 2.5 and 2 and got s=8.875m So total distance would be 28.9m but the textbook ans is 29.9m. Iam not able to get 29.9 m

In Classical Mechanics by Kibble and Berkshire, in chapter 12.4 which focuses on symmetries and conservation laws (starting on page 291 here), the authors introduce the concept of a generator function G, where the transformation generated by G is given by (equation 12.29 on page 292 in the text)...

I don't understand how to find the distance that robot travels in 10s.

I don't know how to solve this