Mechanics Definition and 999 Threads

Dear physics forum dwellers, Currently on search for an advanced fluid mechanics book that covers all the nitty gritty details. Not looking for general introduction books like Munson, Rothmayer, ... or Cengel that are used in bachelor physics classes or engineering classes. Even after skimming...

I have no clue how to do this. Pls help

https://en.wikipedia.org/wiki/Klein%27s_Encyclopedia_of_Mathematical_Sciences Originals are in German or French, the Japanese version cut all the historical content :( Do you think that some day we will see this published in English? Size is big, 20k pages, but it cannot be more interesting I...

I calculated a=8m/s^2. I don't understand how to calculate the total time.

I got the speed of p when q reaches the pulleys = 1m/s, a= 2m/s^2 Iam getting time = 0.8s for q(b)

Friction= 1/(sqroot12)×80 cos 30= 20N I get two equations T-20=8a and 120-T=12a a=5m/s^2 I don't know how to calculate the time. Also with this value of acceleration tension value is wrong and the textbook ans is 84N

A passenger lift had mass 500 kg. The breaking tension of the cable is 12000N. The max acceleration of the lift is 0.75 m/s^2 a) if the lift travels at its max acceleration, calculate the max mass of the passengers: 1)when the lift is accelerating upwards 2) when the lift is accelerating...

A box of mass 20 kg sits on the floor of a lift. A second box of mass 10kg sits on top of the first box and a third box of mass 5kg sits on top of the second box. When the tension in the lift cable is 4260N, the lift is accelerating upwards at 0.5m/s^2. a) work out the mass of the lift. b) work...

A crate of mass 20 kg is put into a lift. The mass of the lift is 300kg. Find the tension in the lift cable. a) when the lift accelerates upwards at 0.3m/s^2 b) when the lift travels at constant speed c) when the lift accelerates downwards at 0.3m/s^2 For (a) is it T- W-w= ( M+m) a Where T is...

Two smooth pulleys are 8m apart at the same horizontal level. A light inextensible rope passes over the pulleys and a box of mass 5kg hangs at each end of the rope. A third box of mass m kg is attached to the midpoint of the rope and hangs between the pulleys so that all the three boxes are at...

Let's play this game, let's assume the infinite Hilbert Space, the operators and all the modern machinery introduced by Von Neuman were not allowed. How would be the formalism? Thanks

A bucket of mass 3kg rests on scaffolding at the top of a building. The scaffolding is 22.5m above the ground. The bucket is attached to a rope that passes over a smooth pulley. At the other end of the rope there is another bucket of mass 3kg, which initially rests on the ground. The bucket at...

A car tows a caravan down a hill. The slope of the hill makes an angle theta with the horizontal, where sin theta = 0.05. The force from the car's engine is a braking force ( a negative driving force). The car has mass 1800 kg and the caravan has mass 600kg. The resistance on the car is 20N and...

A horizontal bar of mass 1kg hangs from a pair of parallel vertical rods of negligible mass, attached to either end of the bar. A third vertical rod is connected to the middle of the bar and a 4kg mass hangs from this below the rod. Work out the tension in each of the rods. I got the tension in...

A car of mass 2000kg pulls a caravan of mass 1200kg along a straight horizontal road. The resistance on the car is 20N and the resistance on the caravan is 80N. The max possible driving force from the car's engine is 1900N. The tow-bar will break if the tension exceeds 680N. a) Find the max...

Two boys are arguing over who gets to play with a toy. The toy has mass 3kg and is at rest on rough horizontal ground with coefficient of friction 0.3. The older boy pulls with a force of 26N at an angle of 39 degree above the horizontal. The younger boy pulls in the opposite direction with a...

It's the 10th question. Iam getting the ans for R=90cos34= 74.6 and F=-30.3N, so I get total contact force by using the formula c= sqroot(f^2+R^2)= 80.52N The ans in the textbook is 92.2N. Iam not getting the right ans for coefficient of friction also which is 0.393

A toy car of mass 80g rolls from rest 80cm down a rough slope at an angle of 16 degree to the horizontal. When it hits a rubber barrier at the bottom of the slope it bounces back up the slope with its speed halved and reaches a height of 10 cm. Find the coefficient of friction between the car...

A book of mass 1.3 kg is on a plank of wood which is held at 16 degree to the horizontal. The coefficient of friction between the book and the plank is 0.45. Find the size of the frictional force. Iam getting the ans by using the formula F= coefficient of friction ×R 5.62N but the textbook ans...

It's the 13th question.

A particle slides up a slope at angle 34 degree to the horizontal with coefficient of friction 0.4. It passes a point P on the way up the slope with 3m/s and passes it on the way down the slope with speed 2 m/s. Find the coefficient of friction between the particle and the slope. Coefficient of...

A boy drags a sledge of mass 4kg from rest down a rough slope at an angle of 18 degree to the horizontal. He pulls it with a force of 8N for 3s by a rope that is angled at 10 degree above the parallel down the slope. After 3s the rope becomes detached from the sledge. The coefficient of...

A wooden block of mass 3.5kg is sliding up a rough slope and passes a point A with speed 20m/s. The slope is at 29 degree to the horizontal. The block comes to rest 25m up the slope. Find its speed as it passes point A on the way down. I calculated coefficient of friction = 0.554. U=20m/s v= 0...

A trolley of mass 5 kg is rolling up a rough slope, which is at an angle of 25 degree to the horizontal. The coefficient of friction between the trolley and the slope is 0.4. It passes a point A with speed 12m/s. Find its speed when it passes A on its way back down the slope. So I did F=m×a...

A certain field has a singularity at the origin, and the divergence of its curl is zero at any point outside the origin, but surface integral of the curl is not zero in the area of any closed surface containing the origin. So how should the Stokes theorem related to this field be expressed at...

All spacecraft that have been put into orbit around other planets have required engines to decelerate them and inject them into their orbits. So-called "ballistic capture", from what I've read, always seems to call for at least a minimum application of force to change the trajectory; I get...

Hi! I am an engineering graduate that took my bachelor's degree in Mechanical Engineering much too long ago, but I have forgotten a lot of the classical mechanics/mechanics of materials theory that I had learned many years ago. I am building a motorcycle right now, and I want to calculate the...

If we prepare a macroscopic system (something like Shrodinger's cat) in a known quantum-mechanical state and we let it evolve for a very long time completely isolated, for what I understand the position of all it's particles will become more and more spread in space. But if the evolution of the...

A box of mass 50 kg is slowing down from 10 m/s on a rough horizontal ground. The coefficient of friction between the box and the ground is 0.3. To start with, the box is being slowed by a string providing a tension of 25N horizontally. Then the string breaks and the box comes to a halt under...

A snooker ball of mass 0.4kg is struck towards a cushion from 0.8m away with speed 3m/s. The surface of the snooker table has a coefficient of friction of 0.3. When the ball bounces from the cushion its speed is reduced by 20%. Find how far from the cushion it stops.

A bag of sand of mass 200kg is being winched up a slope of length 10m which is at an angle of 6 degree to the horizontal. The slope is rough and the coefficient of friction is 0.4. The winch provides a force of 1000N parallel to the slope. At the bottom of the slope the bag is moving at 2 m/s...

As stated, part (a) says that the work done by the gravitational force ##\vec{F_g}## is 59 kJ. If ##W_T## is the work done by the elevator cable during the 12 m fall, then using the work-kinetic energy theorem, \begin{align*} K_f -K_i &= W_g + W_T\\ \frac12m({v_f}^2 - {v_i}^2) &= 59000 + W_T\\...

A gardener is pulling a wheelbarrow of mass 8kg from rest along rough horizontal ground. The coefficient of friction between the wheelbarrow and the ground is 0.6. The gardener provides a force of 50N at an angle of 30 degree above the horizontal as shown in the diagram. a) Find the...

In a factory, a machine picks up a box by clamping it on both sides. The box of mass 4kg is held clamped on both sides by identical clamps with the contacts horizontal. The machine provides a contact force of 50N with each clamp. Find the minimum coefficient of friction between each clamp and...

A chair of mass 6kg is at rest on a rough horizontal floor with coefficient of friction 0.35. It is pulled horizontally by a force of 25N. A boy pushes down on the chair so that the chair is on the point of slipping but remains at rest. Find the force that the boy exerts on the chair.

A box of mass 20 kg is at rest on a rough horizontal ground. Find the magnitude of the total contact force in each of the cases. a) The box is pulled horizontally to the right by a force of 40N b) the box is pushed to the left by a force of 50N at 15 degree above the horizontal . c) the box is...

I understand the idea of a fictitious force. What I am confused about is the energy/potential associated with it. For example, if a cylinder of water is rotating, there apparently exists this centrifugal potential energy, which is obtained by integrating mrw^2 dr. Why is it that the...

This is a not very physics-related question, but I suppose fixing mechanical things involves a bit of physics, so I thought I might as well ask here. I have a Marcato Atlas 150 pasta machine that has stopped working. The crank won't turn because the rollers won't turn. The crank directly drives...

I was having a doubt about the Lagrangian mechanics. Possible we can derive the lagranges equations of by extremisation principle of action, that is assume we already guess what is the lagrangian of the systeme. I say that minimisation procedure rely on assume a lagrangian, and then show it...

I = 2/5M R^2 + Md^2 This is analagous to Earth's movement about the Sun. Is the moment of inertia of Earth about the centre of mass of the Earth Sun system = 2/5MR^2 + Md^2, where: M = Mass of earth, R = Radius of Earth, d = distance from Earth to centre of mass of earth-sun system.

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I noticed the research on NHQM in the following news release. New physics rules tested on quantum computer Published: 19.2.2021 Information for relevant paper is provided as follows. Quantum simulation of parity–time symmetry breaking with a superconducting quantum processor Shruti Dogra...

Hi - i am confused about the following basic mechanics principles Consider a large cubic mass ( mass M ) on the ground with a small cubic mass ( mass m ) placed on top of it. The surface between the 2 masses is frictionless 1 - if a push (apply a force ) to the large cube does the upper...

I assumed that each of the masses attached to the string would be pulled with a force F, instead of F/2, which appears to be the correct value. Why is it F/2? I suspect the fact that the pulley is "weightless" has something to do with the F/2 value. What is it? Thank you.

We were prescribed Goldstein, Taylor and Marion/Thornton for our first course in analytical mechanics, and I'm about to finish up the course but I feel like I have not gotten a good physical, intuitive grasps of the concepts, so I've been trying to read the texts a bit more. Taylor and...

I have heard many times that it does not matter where you put the zero to calculate the potential energy and then ##L=T-V##. But mostly what we are doing is taking potential energy negative like in an atom for electron or a mass in gravitational field and then effectively adding it to kinetic...

There is an interpretation of quantum mechanics out there, and I was not sure if physicists take this seriously, or if it's one of those woo-woo popular misunderstandings of quantum mechanics. So I am posing it to our esteemed physicists here. It says that there can be all sorts of universes...

My proposed solution: When the student stops at the end, suppose the carriage is moving at speed u. 0 = (M+2m)u - m(v - u) ==> u = mv/ M+3m After jumping out, the total momentum of the Carriage + collector system is 0 - mu = -m^2v/ M+3m. By conservation of momentum for the Carriage +...

Consider the following situation: You have 1 rectangular block lying on a table, and an identical block is placed above the block on the table. Now, this new block is constantly pushed to the right, right before it topples off. Consider the torque about an axis passing through the rightmost...

Important note: I only derived the differential equation, I did not solve it. What I think caused the mistake: - the tangent approximation (tan(theta+dtheta) ~ tan theta + d theta