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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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Calculation of the modulus of elasticity of a stretched string

I posted concerning this question a little while ago, not asking for the answer but for an understanding of the setup. Well, I thought I would solve it but I seem to be unable to obtain the required answer. If anyone could help I'd be very…
gnitsuk
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Mass on a stretch elastic string setup

Could anyone dispel my ignorance please. I must be missing something obvious. I'm not looking for the answer here, I just can't visualize the setup. It says that W is attached at point C of an unstretched string where $AC = \frac{4a}{3}$ But the…
gnitsuk
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Mechanics with elastic strings

Two elastic strings, A and B, stretch by 30mm and 60mm respectively when a weight of 4N is attached to each in turn. the strings are hung vertically from the same point, close together, so that when they are unstretched the lower end of A hangs 30mm…
bbr4in
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Phase Angle In SHM

In a simple harmonic motion a trial function $A\sin(\omega t+\varphi)$ is used where $\varphi$ denotes phase angle. What is the work of $\varphi$ in the equation. Doesn't it work for $A\sin(\omega t)$ only?
PiGuy
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Definition of conjugate momentum for more than one independent variables

What is the definition of the conjugate momentum of the function $f$ if the Lagrangian has more than one independent variable, such as: $$L=L(t,x,f,f_x,\dot f, g,g_x,\dot g)$$ where $f=f(t,x)$, $g=g(t,x)$? I know that for a one-independent variable…
user58291
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The second law of Newton for the material points

The material points is massed by springs, found the second law of Newton for every point. I already do this for one point https://i.stack.imgur.com/DFS1D.jpg And get $ \begin{cases} m\ddot{x}= -cx - u\cos{a} \\ m\ddot{y}=-cy - u \sin{a}…
Stepan Vanzuriak
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Rocket velocity relative to decrease in mass due to fuel consumption

A rocket of mass $m$ emits mass backwards at speed $u$ relative to the rocket at a constant rate $k$. Ignoring gravity and air resistance find the speed $v$ at time $t$ if at $t=0$ it has speed $v_0$ and mass $M_0= M + m_0$, where $m_0$ is the…
James Bainbridge
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How does conservation of mechanical energy in a Pendulum work?

How does conservation of mechanical energy in a pendulum work? I understand that gravitational potential energy is converted, as an object falls, into kinetic energy, and is otherwise given by $mgh$, for an object at a height of $h$. $ \ $ So, if…
Stephen
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Find penetration of bullet - classical mechanics

I am studying for my own education form a book and the last part of this question has an answer in the book which I disagree with. Can anyone confirm that it is I or the book that is in error? Here's the question: I have proved the first three…
gnitsuk
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Centre of mass of cone and cylinder combined

A solid right cylinder of radius 3 cm and length 14 cm and a solid circular cone of radius 3 and height 28 cm are joined together at their plane faces. The solids are made of the same uniform material. Given that the centre of gravity of the cone is…
voldetort
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A spherical hailstone is falling under gravity in still air and due to condensation its radius increases, what is terminal velocity.

A spherical hailstone is falling under gravity in still air and due to condensation its radius increases at a rate governed by $\frac{dr} {dt} = kr;$ where $k$ is a constant. Neglecting air resistance show that the hailstone approaches a limiting…
Dan D'silva
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Moment of Inertia of a Square Based Pyramid

I want to find the moment of inertia about the axis perpendicular to the base and passing through the center of mass (z-axis?). Mass is M and height is H and base has sides $a$. I know I can take a slab of the pyramid and take the volume of the…
Sujjan Shaikh
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Mechanics - work, energy and power

A stone of mass 50kg starts from rest and is dragged 35m up a slope inclined at 7 degrees to the horizontal by a rope inclined at 25 degrees to the slope. the tension in the rope is 120N and the resistance to motion of the stone is 20N. calculate…
H.Linkhorn
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Simple Harmonic Motion - amplitude when connected to two springs horizontally.

Image of the full question is here... https://i.stack.imgur.com/dWbcq.jpg The idea of the question is that a particle is attached to two identical springs, the other end of the springs are attached to points $A$ and $B.$ $A , B$ are 4 meters apart…
NumberCruncher
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Calculate distance traveled with opposite force being applied to item travelling

An item moves for $20$ seconds on a straight path with a beginning velocity of $20m/s$. For this entire duration, a force $(X)$ is added to the item which results in this item decelerating at $6m/s^2$. What is the items’ distance from its initial…
Sally
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