Mechanics Definition and 999 Threads

Homework Statement In a physics lab, light with a wavelength λ0 travels in vacuum from a laser to a photocell in a time t1. When a slab of glass with a thickness d is placed in the light beam, with the beam incident along the normal to the parallel faces of the slab, it takes the light a time...

Hi all, I have encountered the idea of a heat bath but am slightly perplexed as to what it is. There was a textbook example that looked to find the number density expression for gas molecules as a function of position (image below). It then said that the probability ##P(z)## of finding the...

I am studying Classical Mechanics in this semester, I want to know if there are any suggestions on some problem sets that will help me to master the skills needed.

Homework Statement CLASSICAL MECHANICS [/B]Homework Equations E=U+K[/B]The Attempt at a Solution Guys, can you please help me with part b) ? I am not sure how to find the velocity. Thanks

My question is can we have negative energy in classical mechanics? Also I would need help for finding the velocity in part b)

Hi all, I have a question relating to the title above. The uncertainty relation tells us that an electron that is localised (in terms of its PDF) is space has a large uncertainty in momentum space. However in classical electrostatics/dynamics we seem to make attempts to do things like...

In quantum mechanics, there exist some systems where the potential energy of some particle is a Dirac delta function of position: ##V(x) = A\delta (x-x_0 )##, where ##A## is a constant with proper dimensions. Is there any classical mechanics application of this? It would seem that if I...

Hello i have the difficulty in solving this two problems..thank you for your help math help boards :-)

Homework Statement Derive an expression for the angle alpha and determine the initial horizontal and vertical forces exerted at the point of attachment of the bell rope to the plank. The system is in static equilibrium Both ropes are light ie negligible mass. The point of attachment has been...

What does it mean the word 'Jet' in fluid mechanics, special when it depends on the free surface?!

Homework Statement Water is supplied at 4.50 m3/s and 415 kPa (abs) to a hydraulic turbine through a 1.0-m inside diameter inlet pipe as indicated in the figure. The turbine discharge pipe has a 1.2-m inside diameter. The static pressure at section (2), 3 m below the turbine inlet, is 25 cm Hg...

Homework Statement A dilute gas of N non-interacting atoms of mass m is contained in a volume V and in equilibrium with the surroundings at a temperature T. Each atom has two (active) intrinsic states of energies ε = 0 and ∆, respectively. Find the total partition function of the gas.Homework...

in the Lagrangian mechanics, we assumed that the Lagrangian is a function of space coordinates, time and the derivative of those space coordinates by time (velocity) L(q,dq/dt,t). to derive the Hamiltonian we used the Legendre transformation on L with respect to dq/dt and got H = p*(dq/dt) -...

Homework Statement A ball A is rotating on a table with an angular velocity ω about its vertical axis. An identical ball B collides with the ball A elastically. After collision the ball A starts sliding over the table. The coefficient of friction is µ. Find: 1) the angle α between the angular...

Homework Statement Show that ##[L_{x}^2,L_{y}^2]=[L_{y}^2,L_{z}^2]=[L_{z}^2,L_{x}^2]## Homework Equations ##L^2 = L_{x}^2+L_{y}^2+L_{z}^2## ##L_x = yp_z-zp_y## ##L_y = zp_x-xp_z## ##L_z = xp_y-yp_x## ##[x_i,p_j]=iħδ_{ij}## ##[L_x,L_y]=iħL_z## ##[L_y,L_z]=iħL_x## ##[L_z,L_x]=iħL_y##...

I have read in several popular physics texts that general relativity predicts that gravity deflects light, but that Newtonian mechanics, in contrast, predicts that the trajectory of light is not affected by gravity. However, I am very skeptical and confused about this result. We of course have...

Homework Statement A circular plate with radius 0.5 m and mass 5 kg is hung on the wall, fixed at a point that is 0.3 m above its center. The plate can freely rotate about the fixed point with no friction. A very short-duration impulse of 5 N sec, along a direction that is tangential to the...

Homework Statement I am revising on the derivation of the differential equation of energy (White's Fluid Mechanics 7th ed) and I'm having trouble understanding the sign convention used in the viscous work term. The textbook first define an elemental control volume and list out the inlet...

When I derive the equations of motion for 2 or more bodies where one is rotating and the other is a mixture of rotation and translation, I get a term multiplying angular velocity squared. I know its right but I don't know what to call it. Can some help me with what to call it (it means C1*ω2...

Homework Statement Assume that block A which has a mass of 30 kg is being pushed to the left with a force of 75 N along a frictionless surface. What is the friction force of block A on block B if the block B has a mass of 24 kg and is accelerating at 0.50 m/s2 to the right relative to the block...

<< Multiple threads on the same subject merged, Thread moved to the schoolwork forums, and the OP has been reminded to show more effort on their own schoolwork questions >>[/color] I want an investigation/research that is simple to experiment practically (I don't have fancy equipment. My main...

Hi everybody, While reading some quantum mechanics book, I met the resolvent formalism which is presented as more powerful than the pertubative approach. For a system with a hamiltonian ## H = H_0 + H_{int} ##, when the interaction part ## H_{int} ## is no more a pertubation but rather having...

Hi! I am Bilal Rajab. I have a question regarding Quantum Physics. From where can we learn about Quantum Physics and what is its relation to Classical Physics? Why is there not one single Physics...? Thanks Regards, Bilal Rajab Abbasi

Hello,I have been going through Griffiths’ Intro To Quantum Mechanics in an attempt to self-teach myself some quantum mechanics. I am currently in section 3.4 (Generalized Statistical Interpretation) I am seeing a “step” occur more than once. When I first came across it, while I didn’t...

I was surprised recently to learn that one of the reasons both Newton and Einstein were so revolutionary was that they performed a neat mathematical trick. For Newton, it was the mathematical derivation of Kepler's laws from Newton's laws of gravitation and motion. For Einstein, it was the...

Are there any folks here who use open source alternatives to Matlab and Mathmatica for visualization of quantum mechanics? Also, are you aware of any introductory quantum material for that tool? If not, do you think such a thing would be worthwhile for visual leaners? Why or why not? I have...

Homework Statement A 28-g bullet is shot vertically into an 6-kg block. The block lifts upward 5mm (see the figure). The bullet penetrates the block and comes to rest in it in a time interval of 0.0010s. Assume the force on the bullet is constant during penetration and that air resistance is...

Assuming generlized variables, q, we have a Lagrangian in mechanics as the kinetic energy, K, minus potential energy, U, with a dependency form such that L(q,dq/dt) = K(q, dq/dt) - U(q) Can someone provide examples of Lagrangians in other disciplines?

So I need to find equations for the force required to tip over a cylindrical object. This is fairly straight forward in the case when the force is applied above the centre of mass, by taking moments about the pivot corner. However, in the case where the force is applied below the centre of mass...

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...

Homework Statement 2. Homework Equations [/B] So I basically have to establish the non linear differential equation that governs the movement of this robot (relates d and theta): The Attempt at a Solution So I know that we should have the sum of torques equal to...

Homework Statement We have a cart (It is very long) and a box on it.They are at first stationary but at ##t=0##, cart begins to move with ##v## such that: ##v = \alpha t^\beta ; t\leq t_0## and ##\dot v = c; t>t_0 ## where ##\alpha ,\beta ,c## are constants. At the time ##t1 (t_1<t_0)## the...

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 A bus is traveling at a constant speed of 6.2ms-1 along a section of road that is inclined at an angle of 6.0degrees to the horizontal. a) the total output power of the engine of the bus is 70kW and the efficiency of the engine is 35%. calculate the power to the engine b)...

Hi, I'm an undergrad, following my very first serious course in QM. We're following Griffith's book, and so far we're staying close to the text in terms of course structure. Griffiths starts out his book by postulating that each and every state for any system \Psi must be a solution to the...

[Moderator's note: Post spun off from another thread.] That is correct but it doesn't mean Eo=0. The rest energy is unlimited in classical mechanics. Therefore it is impossible to find a relation between total energy and momentum.

Can anyone please explain to me how can I calculate the "Tension" and "acceleration" of M in this question interms of M,m1,m2 and g? I can't understand how M has an acceleration or why M is involved in the calculation of the tension my solution was that acc of M is zero and Tension = m1g x...

Homework Statement Think that we have only conservative force in this question and no nonconservative force like friction exists. Also## U ##means potential energy (eg Gravitational Potential Energy),##K## means Kinetic Energy (##1/2 mv^2##) and ##E = K + U = constant## We have a arbitrary...

Homework Statement .A cylinder P of radius rP is being rotated at a constant angular velocity ωP along positive y-axis with the help of a motor about its axis that is fixed. Another cylinder Q of radius rQ free to rotate about its axis that is also fixed is touched with and pressed on P making...

Hi, I am reading Landau-Lifshitz course in theoretical physics 1. volume, mechanics. The mechanics is derived using variatonal principle from the start. At first they start with point particles, that do not interact with each other. Thus the equations of motions must be independent for the...

I was thinking about this and couldn't really figure it out. You are standing on a cliff and you have two identical balls. In this case, air resistance is to be ignored. The only thing different is that you throw the ball horizontally at different speeds. Let's say you threw ball one at a speed...

Imagine you have a vertical pressure head 2m tall with water flowing down to height 0m and emptying. Through this length we have 3 identical tubes of resistance R and length L. Assuming I know the volumetric flow rate(Q) as a function of height, how can I calculate the resistance of each tube...

I study on quantum mechanics and I have question about operator. In one dimension. How do we know ## \hat{x} = x## and ## \hat{p}_{x} = -i \bar{h} \frac{d}{dx} ## When schrodinger was creating an equation, which later called "the schrodinger equation". How does he know momentum operator equal...

Homework Statement Homework Equations E=T+U T=1/2 mv^2 U=∫F⋅dr The Attempt at a Solution Part 1 Work x=x-dot y=y-dot z= z-dot r=r-dot θ=θ-dot [/B] T= 0.5m(x^2 +y^2) 0.5M(z)^2 Changing to polar coordinates T=0.5m(r^2 +rθ^2) 0.5M(z)^2 U=-Mgz E=T+U =0.5m(r^2 +rθ^2) 0.5M(z)^2-Mgz z=L-r...

Homework Statement The problem states that there is a father pulling a 100 lb sled with a force of 100 lb at some angle. At what angle does the father have to pull in order for the sled to accelerate at 25 ft/s^2? The coefficient of kinetic friction here is given as 0.04. Homework Equations F...

Homework Statement I'm supposed to find the normal force acting on the box by the slab as a function of time. The problem is I don't know what the constraint is. I can't find the relation between r and theta that adds the two up to zero. Homework Equations Lagrangian equation. The Attempt...

Homework Statement A yoyo falls straight down unwinding as it goes, assume has inner radius a, outer radius b and Inertia I. What is the generalised coordinates and the lagrangian equation of motion? Homework Equations L=T-U where T is kinetic energy and U is potential The Attempt at a...

I am confused with this concept. So if a system possesses multiple possible eigenfrequencies (and therefore modes), how does the system "know" which eigenfrequency will it want to vibrate on? Does that depend on the initial condition you give the system? Is there any mathematical relation...

We know that energy is a function of space and velocity and it’s constant (in ideal case) though time. So ## E(\vec{x}(t) , \vec{\dot{x}}(t)) = E_0## where ##\vec{x} , \vec{\dot{x}} \in \mathbb{R}^3##. So my function is ##E : \mathbb{R}^6 \rightarrow \mathbb{R}##. Then there is my question...

hi, I’ve been walking through posts on this forum, and found plenty of book recommendations for QM. My problem is, I haven’t had enough practice in a long while. I could go over Solved Problems in e.g. Galitsky, or Gasiorowitz, but they seem to be a little far from what I want to test...