# Tagged Questions

Newtonian mechanics covers the discussion of the movement of classical bodies under the influence of forces by making use of Newton’s three laws. For more general discussion of energy, momentum conservation etc., use classical-mechanics, for Newton’s description of gravity, use newtonian-gravity.

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### Physics Chain Problem

A chain of length d lies on a table, $d/4$ of it hangs loose on the side of it. Friction coefficient is 0.2. It is released and begins to slide. What is the final velocity with which it falls of the ...
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### Heliocentric to barycentric coordinates

I have a system with a central body and "particles" orbiting around it. The system is described in heliocentric coordinates. I am trying to obtain the velocity of the central body in barycentric ...
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### Why did Newton state his first law separately even though it is apparently a direct consequence of the second law? [duplicate]

If $F=0$, $F=ma \implies m\frac{(v-u)}{t}=0\implies v-u=0 \implies v=u$ Which is essentially Newton's first law.
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### The components of applied forces on the masses of a Trebuchet

Background information: I was following an online mechanics document in order to learn how to derive the equations of motion for a trebuchet (shown below) using Lagrangian mechanics. At some point ...
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### Problem in understanding in the derivation of torsion acting on a circular shaft fixed at one end

My doubt is how Arc(ab) = L $\gamma$. Arc (ab) = R$\theta$ makes sense as that's the arc of that circle.
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### Equation of a bifilar pendulum?

I am just wondering how I find the equation of a bifilar pendulum? I have not found one on the internet, and have come across two different equations, neither of which give the result I have found ...
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### Conceptual understanding behind moments of force for a rigid body cylinder

I have a question behind the conceptual understanding of the following equation: $$\frac{\text{d}}{\text{d}t}\mathbf{L}_G = \sum_i \ \mathbf{r}_i\times \mathbf{f}_i$$ where $\mathbf{L}_G$ is the total ...
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### What's behind the moment of inertia and other “body-global” properties of bodies?

I'm an electrical engineer currently doing some (computational) mechanics stuff. In introductory literature about mechanics, you can read plenty about the moment of inertia and how you use it in ...
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### Force on a free body [duplicate]

What would happen if we apply a force on a rod unbound by any forces, considering that the force always acts at the end of rod and is always perpendicular to the length of the rod ? I wanted to ask ...
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### Standing waves: why do 2 standing waves don't cancel each other?

I have learned that when two waves are combined, the peaks and troughs could be in the same direction (so that means the amplitude is increased) or the peaks and troughs could be in the opposite ...
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### Solving 9 variable Normal Reaction equations of Sudoku board [closed]

We have a rigid Square board of negligible mass, which has been divided into a grid of 9 small squares(like a Sudoku Board), at centre of each square a point mass is attached. The gravity on the board ...
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### Conservation of mechanical energy when object strikes the ground

When I raise a pen, the external work I do gets stored in the form of potential energy hence the mechanical energy is increased. When I leave the pen the pen starts falling and as the potential energy ...
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### Orbits for dummies [duplicate]

In a certain universe a perfectly spherical, uniformly dense planet is found to be in a stable orbit around a stable star. The rest of the universe is empty space with no silly stuff like dark matter. ...
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### Will the ball come out of the well or not?

A small ball moves at a constant velocity $v$ along a horizontal surface and at point $A$ falls into a vertical well of depth $H$ and radius $r$. the velocity of the ball forms an angle $\theta$ with ...
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### Finding the height of a balloon [closed]

A balloon moves up vertically such that if a stone is thrown from it with horizontal velocity $u$ relative to it, the stone always hits the ground at a fixed point $2u^2/g$ horizontally away from it. ...
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### Maximum angle that a wheeled body can climb at

I've only recently been introduced to the concept of static vs dynamic friction and I was looking to check my understanding by determining the max angle a wheeled body can climb. In the diagram below ...
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### What is y(x,t) = Acos(kx - wt)? [closed]

Im very new to wave mechanics and I've come across the following wave equation. I know this is asking too much,but I wanted to know what is the significance of this equation? what does it tell us / ...
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### What force is needed to put an object 200m into the air? [closed]

How much force (is that the word I am looking for?) is needed to put a 60kg weight 200m into the air using a lever? Essentially flinging the weight into the air, eg someone throwing a ball into the ...
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### Are tides just very very very weak spaghettification?

I was wondering as to why there are two tidal bulges instead of just one on Earth, and then I saw this diagram: The oval shape that the Earth's water is transformed into in this image reminded me of ...
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### Why does the centrifugal term involve a vector originating from the center of Earth? [closed]

Why in every mechanics/dynamics book I look the centrifugal force due to Earth's rotation is measured from "the center of Earth"? For example in Marion's dynamics, the fixed inertial axes are placed ...
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### If water is essentially incompressible, why are there tides?

So recently we were taught in school that tides are formed because the moon 'cancels out' some of the earth's gravity, and so the water rises because of the weaker force. But if water is not ...
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### Earth mass redistribution

Knowing we haven't imported construction materials from space has mankind altered the earth's weight through time due to building work? Or will it remain constant?
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### What is The force a body exerts on a vertical circular track?

I am trying to calculate the force a body exerts on a vertical circular track with no friction at its highest point I know the centripetal force at that point is mg and the given data is the velocity ...
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### Why is the simple harmonic motion idealization inaccurate?

While in my physics classes, I've always heard that the simple harmonic motion formulas are inaccurate e.g. In a pendulum, we should use them only when the angles are small; in springs, only when the ...
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Yesterday i got a MCQ in exam that a body in projectile motion with initial velocity 20m/s creating an angle of 60 degree with horizontal. What is its velocity at max. Height (A) 10m/s Or ...
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### Terminal velocity after vertical launch

If an object is launched directly up at its terminal velocity, will it have enough time/energy to reach its terminal velocity again before it hits the ground, or will drag prevent this? In this case, ...
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### Which timestep should I use for a $N$-body simulation of the Solar system?

I am trying to implement a $N$-body simulation of the Solar system and I am stuck on the issue of the simulation timestep size. At first I would like to use a simple Euler stepping scheme. Knowing ...
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### normal force on a physical pendulum [duplicate]

I have read and understood that a normal force has got nothing to do with torque on a physical pendulum. But I can't understand in which direction the normal force points to. Can someone help? This ...
Suppose we have a lever $AB$ of length $1m$ and that the fixed point is $O$ and $AO=0,3m$. If in $B$ I have a down vertical force of $F_1=5N$, find the force $F_2$ applied in A that guarantees the ...