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Questions tagged [classical-mechanics]

For questions on classical mechanics from a mathematical standpoint. This tag should not be the sole tag on a question.

Wikipedia says:

Classical mechanics describes the motion of macroscopic objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft, planets, stars, and galaxies. Besides this, many specializations within the subject deal with gases, liquids, solids, and other specific sub-topics. Classical mechanics provides extremely accurate results as long as the domain of study is restricted to large objects and the speeds involved do not approach the speed of light.

For questions on classical mechanics from a mathematical standpoint. This tag should not be the sole tag on a question. Examples of other tags that might accompany this include , , and .

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Where does this $F_2$ come?

The force diagrams show the weights $W_A$ and $W_B$ of the blocks, directed down. $F_1$ is the force of block $B$ on block $A$, while $F_2$ is the force of $A$ on $B$. Reference:- An introduction to mechanics by Kleppner D And Kolenkow R My…
Math geek
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Work function and potential energy in a Lagrangian

I would like to know the difference between work function and potential energy . Below attached are 3 questions: In question 1 the potential energy is used to calculate the Lagrangian whereas in question 5 work function is used. Why is it…
Sharmi C
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Lagrangian of a system of 2 rods

For the above question I have proceeded in following way: However I am unable to proceed and am unable to use $\theta$ in any further equation. I think I am getting the concept wrong somewhere. For the second part I have proceeded in the following…
Sharmi C
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Lagrangian of a system

I have a doubt regarding finding Lagrangian of a body on an inclined plane. Attached below are excerpts of 2 problems from a classical mechanics book that I am referring to. In the above question, while calculating potential energy V, the height…
Sharmi C
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lagrangian and hamiltonian of bodies rolling on an inclined plane

I have 2 questions where I have some difficulty in the solution method shown in the books. In case of the question number 5 I DONOT understand why there is an $mga cos \theta$ in the equation of potential energy. Next Here in the above question I…
Sharmi C
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Calculating the Lagrangian and the equation of motion.

A mass $m$ is attached to the end of a light inextensible string, which is wound around a cylindrical wheel of radius $a$. The moment of inertia of the wheel, about an axis perpendicular to the wheel, is $I$. The axis of the wheel is horizontal,…
MathGeek1998
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Rod vs string in vertical circular motion

The first two conditions make intuitive sense for rods/wires. In order to reach the top, the bead/particle must have a positive velocity at that point. However, I do not understand why the 3rd condition is necessary for a string. I can imagine a…
jamie
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Circular motion on banked road

Independent of the specific problem in question, I do not understand why $Rsin\theta=mv^2/r$. Surely the centripetal force and $Rsin\theta$ are acting in the same direction(left on diagram), since centripetal is acting towards the centre of the…
jamie
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Two Year 2 Edexcel Mechanics A Level questions

Chapter 5 Edexcel Mixed Excercise 5 Question 9 and Challenge Question. First, question 9 part (a): I did $\ F = 700 + 2150 \times9.8\cos10 ^\circ = 4400N \ (2sf)$. But the answer in the back is $3700N$. They forgot to include the $700N\ $ or I am…
Adam Rubinson
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A Level moments of skateboard on a rail - justification for ignoring normal reaction forces

Consider question 2. $$$$ $$$$I'm fairly confident I can answer each part of the question if we assume that the normal reaction forces are all concentrated at point C. However, what is the justification for assuming the forces are concentrated at C…
Adam Rubinson
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The Ratio of Unknown Velocities

A ball is projected vertically upwards from ground level with speed u1. At the point when this ball is at its maximum height, another ball is launched with initial velocity u2. The two balls fall back on the ground at the same time and do not…
AOD
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Using Total Distance to Calculate Velocity (AS Level Mechanics)

A particle travels in a straight line and decelerates uniformly at 2m/s/s. When t=0, its velocity is u m/s and when t=100 its velocity is -v m/s (where u>v>0). The average speed of the particle over the 100 seconds is 62.5 m/s. Find the values of u…
AOD
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String across hoop

A circular hoop of radius is stood vertically on a flat surface and held in place. A smooth wire is tightly stretched between the upmost point of the hoop and a point on the hoop at height ℎ. A bead of mass is held at rest at the top of…
jamie
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Finding the maximum load allowed in a lift.

A lift of mass $520kg$ is supported by a steel rod attached to its bottom. The rod can withstand the maximum thrust $15,400N$. The lift can accelerate at $2.5ms^{-2}$ and decelerate at $7.8ms^{-2}$. Find the maximum allowed load in the lift. This…
Jamminermit
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Looking to find the distance from not the center of the earth to a point on the surface

I am looking to find the distance from a point on the earth's surface to a fixed point within the earth, not at its center. This fixed point would not be on either of the earth's axis. It would be 10 km away. I want to code this into some software…
Monte Dreyer
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