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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Geometry in diagonal matrix and inertia tensor

For this problem, can anyone explain to me why when $x_1$ axis is aligned with the diagonal of the cube, the resulting inertia tensor will become diagonal? How to interpret this result geometrically? ...
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Intuitive understanding of centripetal vs. centrifugal force

I am having trouble understanding how centripetal force works intuitively. This is my claim. When I have a mass strapped on a string and spin it around, I feel the mass pulling my hand. So, I want ...
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Object Pushed by Multiple Forces [duplicate]

If we have a general object and we have multiple forces acting on it at several points. Assuming we know the center of mass, mass and moment of inertia of the object: Will the object rotate only ...
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Will an object resting on a rotating platform move in a frictionless world?

Imagine that a pebble is placed on a uniformly rotating, frictionless disk. What will happen to this pebble? Will the disk slide under it and the pebble stay as is? Or will there be a centrifugal ...
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Direction of friction when a car turns

When a ball moves to the right, friction acts to oppose the motion, in other words, to the left. However, when a car travels around a bend, the friction acts in the perpendicular direction to the ...
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Linear motion with variable acceleration

Consider the following problem I pull a mass m resting at x = 0 on a frictionless table connected to a spring with some k by an amount A and let it go. What will be its speed at x=0? I know how to ...
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Why are four-legged chairs so common?

Four-legged chairs are by far the most common form of chair. However, only three legs are necessary to maintain stability whilst sitting on the chair. If the chair were to tilt, then with both a ...
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Proof that the Earth rotates?

What is the proof, without leaving the Earth, and involving only basic physics, that the earth rotates around its axis? By basic physics I mean the physics that the early physicists must've used to ...
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Intuition as to why the orientation (of a 3D object) is not a conserved quantity?

Say you start off floating in space, in a fixed position and orientation, with zero linear and angular velocity, with no external forces. So you are a closed mechanical system. By twisting your body ...
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Is there an intuitive reason the brachistochrone and the tautochrone are the same curve?

The brachistochrone problem asks what shape a hill should be so a ball slides down in the least time. The tautochrone problem asks what shape yields an oscillation frequency that is independent of ...
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Could someone jump from the international space station and live?

Felix Baumgartner just completed his breathtaking free-fall skydiving jump from $120,000\,\text{feet} = 39\,\text{km}$ above the Earth, breaking the speed of sound during the process. I was wondering ...
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Physical meaning of the angular momentum

Still reading Classical Mechanics by Goldstein, I'm struggling on a very basic notion: angular momentum. I physically understand it as the momentum of an object rotating around something given a ...
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Newton's cradle

Why, when one releases 2 balls in Newton's cradle, two balls on the opposite side bounce out at approximately the same speed as the 1st pair, rather than one ball at higher speed, or 3 balls at lower ...
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What do people actually mean by “rolling without slipping”?

I have never understood what's the meaning of the sentence "rolling without slipping". Let me explain. I'll give an example. Yesterday my mechanics professor introduced some concepts of rotational ...
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Is the normal force a conservative force?

Most of the time the normal force doesn't do any work because it's perpendicular to the direction of motion but if it does do work, would it be conservative or non-conservative? For example, consider ...
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Block on a block problem, with friction

Consider two blocks, one on top of the other on a frictionless table, with masses $m_1$ and $m_2$ respectively. There is appreciable friction between the blocks, with coefficients $\mu_s$ and $\mu_k$ ...
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Trouble with classical mechanics self-learning (How to avoid going down the Physics rabbit hole?) [duplicate]

I'm a retired police officer trying to learn classical mechanics on my own. I have gone through many links on the Internet including the classical mechanics quick reference textbooks from Physics ...
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Proving Kepler's 1st Law without differential equations

Is there a way to show that motion of Earth around the Sun is elliptical (Kepler's 1st law) from Newton's laws without resorting to the use of differential equations of motion?
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Why doesn't the speed of Earth (moving through space) kill us?

I have read different speeds of Earth in different sources. $382\;{\rm km}/{\rm s}$, $12\;{\rm m}/{\rm s}$ and even $108,000\;{\rm km}/{\rm h}$. Basically, it's moving too fast around the Sun. And the ...
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How can the contact point of rolling body have zero velocity?

They say that for a rolling body, the velocity of the contact point is zero. I'm not getting this. How can it be zero when it's in continuous motion?
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Does Newton's third law apply to momentum or to forces?

I read all the previous answers concerning the 3rd law and I have seen that it is definitely not universal, (Edit: but conservation of momentum is. If it is not universal it should be not a problem to ...
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Why are Saturn's rings so thin?

Take a look at this picture (from APOD http://apod.nasa.gov/apod/ap110308.html): I presume that rocks within rings smash each other. Below the picture there is a note which says that Saturn's rings ...
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Can superconducting magnets fly (or repel the earth's core)?

If a superconducting magnet and appropriate power supply had just enough $I\cdot s$ (current $\cdot$ length) so that when it was perpendicular to the earth's magnetic field, the force of the ...
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Why there is a 1/2 in kinetic energy formula? [duplicate]

Possible Duplicate: Why is there a $\frac 1 2$ in $\frac 1 2 mv^2$? Hèllo, I have a question about kinetic energy formula. As you know, in kinetic energy formula, we have: ...
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Conservation of momentum when rain pours into a wagon

Suppose a wagon is moving at constant velocity on a friction-less surface, and rain begins to fill the wagon. The net force on the wagon is zero, so momentum is conserved; as the mass of the wagon ...
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Which is easier, pushing or pulling?

It is generally assumed, from a person's perspective, that pushing a cart is more easier than pulling one. But why? Is there any difference in terms of force required to achieve the same amount of ...
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Can you completely explain acceleration to me?

I understand what acceleration is, and I know the formula, and I understand it's a vector. I just don't understand how the equation works exactly. I'm kind of picky, I know, but bear with me. ...
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Confusion with derivation of fictitious forces

I read the mathematical derivation of fictitious forces on Wikipedia and I'm having trouble understanding it. I went on a few other sites looking for a better derivation, but they're all basically the ...
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3answers
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Analyzing the motion of a ball rolling without slipping inside a hemispherical bowl

Consider a solid ball of radius $r$ and mass $m$ rolling without slipping in a hemispherical bowl of radius $R$ (simple back and forth motion). Now, I assume the oscillations are small and so the ...
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3answers
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Why does the cart move? [duplicate]

A while ago someone proposed the following thought experiment to me: A horse attached to a cart is resting on a horizontal road. If the horse attempts to move by pulling the cart, according to the ...
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How many points are required to make a black box

I have a black box with an arbitrary mass distribution inside it. I want to replace that object with n point masses without changing any mechanical properties of the box (center of mass, total mass, ...
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2answers
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Might a planet perform figure-8 orbits around two stars?

Might a planet perform figure-8 orbits around two stars? I'm thinking that if the two stars were equal mass (and not orbiting each other) then a planet that were to go right between them would ...
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How is distance between sun and earth calculated?

How has the distance between sun and earth been calculated? Also what is the size of the sun?
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Newton's Third Law Exceptions?

Lately I've been brushing up on some of my old Physics texts from college. Most recently, I've been rereading parts of "Classical Dynamics of Particles and Systems (5th ed.)" by Thornton and Marion. ...
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Why does a conservative force return the work done against it by a body to that body?

Newton's 3rd law of motion: Newton's third law of motion or the law of action and reaction implies that there is no isolated force in nature. Whenever there is any force at all , there must be ...
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Defy gravity torques with gyroscopes?

Context On the following drawing, a platform is hung from the ceiling not exactly from its centre of gravity. Because of this it can't sustain an arbitrary orientation for long; I want to increase ...
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How long must escape velocity be maintained?

Escape velocity from Earth's surface is 11.2 Kilometres/second. How long would one need to maintain this escape velocity to actually escape Earth's gravitational pull? Must this 11.2 km/s velocity ...
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How to explain independence of momentum and energy conservation in elementary terms?

I'm trying to explain to someone learning elementary physics (16 year old) that linear momentum and energy are conserved independently. I'm not a professional physicist and haven't tried to explain ...
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Moment of Inertia, why $r^2$and not $r$?

So my engineering mechanics book includes a brief discussion on area moments of inertia. Unfortunately, the ensuing chapter is predominately computational in nature. I don't have a thorough grasp of ...
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Can an object accelerate to infinite speed in FINITE time (Newtonian)?

Obviously this is impossible in relativity; however, if we ignore relativity and use only Newtonian mechanics, is this possible? How (or why not)?
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Infinities in Newtons law of gravity (for point particles)

Newtons law of gravity for two particles of mass $m_1$ and $m_2$ is: $G\frac{m_1.m_2}{r^2}$. Supposing that the particles are point particles then gravitional attraction will bring them closer ...
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4answers
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Is acceleration an absolute quantity?

I would like to know if acceleration is an absolute quantity, and if so why?
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Proving angular momentum is conserved for a particle moving in a central force field $\vec F =\phi(r) \vec r$

A problem I am trying to work out is as follows: A particle moves in a force field given by $\vec F =\phi(r) \vec r$. Prove that the angular momentum of the particle about the origin is constant. ...
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How does one determine an inertial frame?

How does one determine whether one is in an inertial frame? An inertial frame is one on which a particle with no force on it travels in a straight line. But how does one determine that no forces are ...
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What in Newton's three laws of motion is original and not a paraphrasing of his predecessors?

The three laws are: First law: The velocity of a body remains constant unless the body is acted upon by an external force. Second law: The acceleration a of a body is parallel[disambiguation needed ...
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Explaining Newton's Laws of motion to a 6 year old

An old professor of mine once said that an effective means to get people interested in Physics is to get them started early. What would be an effective and meaningful (and fun) means to explain ...
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Finding optimal angle for projectile, taking into account linear (Stokes) drag

If you throw a projectile from the ground at a certain angle, it's not hard to see that, assuming we're in a vacuum, throwing it at 45º from the ground will always make it go farthest before it hits ...
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How can the linear momentum can be understood physically?

Currently reading Classical Mechanics by Herbert Goldstein, and I'm trying to understand every concept physically. Speed can be understood physically, as the distance traveled within a certain amount ...
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Won't the test charge disturb the electric field to be measured?

As written in Principles of Physics by Halliday, Resnick and Walker: The electric field is a vector field; it consists of a distribution of vectors,one for each point in the region around a ...
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Variation in measurements of $g$ on the Earth's surface due to the Moon's gravity

A book, Exercises for the Feynman Lectures on Physics, has recently been published. It consists of homework problems to provide practice with the techniques and concepts used in the famous Feynman ...