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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187 views

Is momentum truly conserved? [closed]

Suppose I have a system of a person holding a rock on a frictionless sheet of ice. He throws the rock at an angle above the horizontal to propel himself off the ice. Is the momentum of that system ...
2
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3answers
211 views

Terminal velocity and distance traveled with constant but limited power

I'm trying to model how far to move an object over time according to a power applied resisted by friction. So maybe... an object accelerates at a certain rate until the power provided can no longer ...
0
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1answer
36 views

How do I calculate the speeds in x, y, and theta of a spinning rod?

Suppose the object looks like the diagram below (it is the horizontal rod). On the vertices, are two velocity vectors $v_r$ and $v_l$. The question is: how is the motion of the rod affected by these ...
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2answers
51 views

What is a center of gravity?

I have tried to search the definition of it up on Google, but the explanations of center of gravity were very confusing and I had trouble understanding them. Can you explain to me what center of ...
3
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1answer
131 views
0
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1answer
116 views

Physical meaning of eigenvectors of mass matrix

What is the physical meaning of the eigenvectors of the mass matrix? If I consider a 2-dof system with one mass linked to two orthogonal springs and I write the equations in any orthogonal system of ...
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3answers
114 views

Path followed by centre of mass of a ball when ball breaks up in two parts due to internal stresses

A ball was moving along a parabola and it breaks up into two parts. How can I say that the centre of mass will follow the same parabola ? I know that ( for simplicity I am assuming that the ball is ...
2
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0answers
124 views

Lagrange: when a potential force, when a generalized force?

Consider the following case of a drum unrolling a mass that is on a massless string wrapped around the drum: According to my professor, here we must consider the mass $m$ being in a gravitational ...
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2answers
549 views

Half-atwood machine with accelerating pulley

This is a follow-up to my previous question, in which I am now trying to calculate the acceleration of the cart (as before, the block surfaces are frictionless). The mass $m_2$ is attached to $M$ via ...
1
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3answers
396 views

How is normal force distributed along the surface of contact?

Help me settle this argument. A mass $m$ is placed on a thin diving board. The base of the diving board has mass $M>>m$. Does the board tip over? I drew the following FBD and concluded there ...
4
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2answers
129 views

Physical intuition about the inertia tensor

I'm studying Mechanics on Goldstein's book (Classical Mechanics) and Spivak's book (Physics for Mathematicians) and I'm in doubt about the physical intuition about the inertia tensor. On both books, ...
1
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1answer
38 views

Speed of different inclined plane [closed]

Assume friction-less, an object was release from the top, what is its speed at the lower end of the slope? I tried $v= \sqrt {2*9.0m/s^2*5m}$, but I doubt if it's a correct answer, any help?
2
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1answer
49 views

Given an equation of an elliptical orbit, is it possible to find satellite´s speed at a certain point?

As the heading says: given an equation of an elliptical orbit, is it possible to find satellite´s speed at a certain point? I'm playing a bit with simulations of planets and satellites in the solar ...
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2answers
57 views

Why time of flight remains same for a projectile even though collision takes place?

Why time of flight remains same for a projectile even though collision takes place ? Suppose a ball is projected with some velocity V with some angle θ the the time of flight is T. Now if another ...
1
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0answers
57 views

Hollow Iron pipe electromagnet? [closed]

How strong would a electromagnet be if I use a hollow Iron pipe as the core? The thickness of the pipe will be 2-3 cm. How much weaker would this electromagnet be compared to a non-hollow ...
0
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1answer
108 views

Torque when net external force is zero

I was studying force couple and my teacher said that in this the torque about any point is same. That led me to wonder if in any case if net external force is zero then is torque about any point in ...
1
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1answer
92 views

Contradiction in a simple torque/rotation problem - two ways of calculating external force don't agree

Suppose we have a rigid system of two point objects (both of unit mass) connected with a massless rod, with the objects horizontal on the x axis, at a distance $r_1$ and $r_2$ from the origin, ...
1
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2answers
121 views

Kinetic energy and work confusion [closed]

I know that $\frac{1}{2}mv^2$ is derived from $W = \int \vec F \cdot\ d\vec s$, but are there exceptions to the kinetic energy formula? Newton says that unless an external force is applied, a body ...
1
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2answers
61 views

Exercise pulleys and accelerations [closed]

The system shown has ideal massless pulleys and no friction. The pulleys 1 and 2 are fixed and the pulley 3 is mobile. The mass m2 is rigidly attached to the center of the pulley 3 by a support ...
1
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1answer
52 views

Gravitational PE lost v Elastic PE gained in mass - spring

If a spring has a load $m$ added to it (and so is extended by $x$), the gravitational potential energy lost by the mass will be $mgx$. The elastic potential energy gained by the spring is ...
3
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4answers
320 views

Conservation of momentum in a baseball

Conservation of momentum: A thought experiment. A baseball is placed on top of a baseball holder, the kind used to train young batters. A batter hits the stationary ball perfectly horizontal, sending ...
4
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0answers
125 views

Alternate Formulation of Kinetic Energy for Lagrangian

So I have a question regarding this system: It is supposed to be a simple model of an aircraft with the fuselage idealized as a concentrated mass $M_0$ and the wings modeled as rigid bars carrying ...
2
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2answers
374 views

Pulley system on a frictionless cart

Let's say you have a pulley set up as below on a cart, with a massless pulley and string. The mass hanging off the side is attached via a rail, and all surfaces & pulley are frictionless except ...
4
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0answers
46 views

What is the specific source(s) of sliding kinetic friction

In simplistic (K-8) physics classes, it seems to be generally instructed that the friction between two moving surfaces is due to the unevenness of each surface and the microscopic roughness. However, ...
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1answer
106 views

How can we apply Newtons laws, or kinematics to solve a problem like this one?

Problem: Two objects with masses 5.00 kg and 2.00 kg hang .600 m above the floor from the ends of a cord 6.00 m long passing over a frictionless pulley. Both objects start from rest. Find the maximum ...
2
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0answers
24 views

Initial conditions for a massive objects to follow a path

Suppose I have a path, such as the one traced out by $r^2 = \cos(2\theta)$, and $n$ objects with mass $m$ at equidistant points on this path. What velocities should each object initially have in order ...
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2answers
443 views

Tension in rope between falling objects

I got a mass m connected with a rope to a mass 2m which is centered directly underneat it. The masses are falling with a constant speed v. Would it be correct to say that the tension in the string is ...
2
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1answer
103 views

Physical interpretation of the canonical scalar product in linear dynamics

Consider a unforced, undamped, linear mechanical system with a finite number of degrees of freedom. Its (second order) dynamical equations can be gathered in a matrix equation $$M\ddot X + K X=0$$ ...
1
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1answer
177 views

What keeps the ball moving?

I push a ball which is at rest and then it starts moving. I have done some work on the ball. Assume that the plane is frictionless. The ball would continue moving, based on the principle of inertia, ...
0
votes
1answer
151 views

Block being pulled from rest on a frictional surface [closed]

An initially stationary block of mass $m$ has a force, $F = 0.500mg$, applied to it at an upward angle $θ = 20˚$ above the horizontal. What is the acceleration of the block if the frictional ...
1
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2answers
59 views

How can make myself sure that I can apply Conservation of Momentum in a system?

How do I know I can apply Conservation of Momentum in the System ? And What happens if there is a Impulse in the system?
0
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3answers
220 views

Deceleration of a bullet [closed]

Taking into account gravity, air resistance, and wind velocity and direction. (And also temperature if it's actually relevant.) I know the muzzle velocity, the total distance the bullet traveled, its ...
0
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1answer
49 views

Definition of unit of force [closed]

As we know $1\ \mathrm{N}$ is the force which can accelerate $1\ \mathrm{kg}$ mass with $1\ \mathrm{m/s^2}$ acceleration. But for which surface is this definition given? I mean a $1\ \mathrm{kg}$ ...
2
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3answers
120 views

What has the potential energy: the spring or the body on the spring?

Particles have gravitational potential energy due to its position in the gravitational field. We say the particle has potential energy and not the Earth (the body doing the work). Why is it not the ...
0
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0answers
44 views

Given Newton's 3rd Law, how is a sea-pumped hydro jetpack possible? [duplicate]

EDIT: I dont think it's an obvious duplicate. That Q just asks how a water jet pack works. My Q asks how 2 forces in 2 opposite directions producing 2 opposite-equal reactions can somehow produce a ...
1
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2answers
180 views

How to calculate force / torque on non-flat lever, i.e. dolly

See attached image. The mass is being rotated on a lever where the pivot point (P) is a certain distance ($L_2$) from the right angle at the bottom. How do I calculate the force necessary to apply ...
1
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1answer
80 views

When to use a whole vector approach vs an energy approach?

My professor has just introduced two new ways to solve projectile motions. One approach involve using trigonometry and vectors and the other involves using the idea of conservation of energy. My ...
0
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1answer
68 views

State of academic fields of analytic mechanics and Multi Body Dynamics (MBD)

My question essentially contains two parts: one practical question and one philosophical question. Background I am an engineering student working in the field of Multi Body Dynamics (MBD). My ...
1
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1answer
177 views

What does the free body diagram for mass 1 look like?

In this situation: Enough tension is applied towards the right on $m_2$ so that $m_1$ starts sliding backwards. I am confused about what the free body diagram for $m_1$ looks like. Here is my ...
0
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2answers
428 views

Electromagnet Electricity Consumption?

Wikipedia states that - The only power consumed in a DC electromagnet is due to the resistance of the windings, and is dissipated as heat. Is this true? So powerful magnets like junkyard magnets ...
0
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2answers
75 views

Compression of spring when an object of given mass is placed on it

A question in my textbook says - A block of mass $m$ is released from rest onto an ideal non deformed spring from a negligible height. Neglecting air resistance, find compression $x$ of the spring. ...
0
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2answers
51 views

Can an Adequately Long Tube Float?

I was just pondering in my head one day (I don't recall what I was pondering), but I came across the thought: If an adequately long (and light) tube is placed in the atmosphere, can the difference in ...
1
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1answer
80 views

car suddenly stop on hill/ circular motion

For car a it's simple, kinetic friction= mass*9.8*1.0 kinetic friction =mass*9.8 a=kinetic friction/mass=9.8m/s^2 but for car 2 is what i would like to ask about: the centripetal acceleration is ...
0
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1answer
43 views

Maximum displacement of a projectile with $x$ initial velocity and drag resistance

So, as a personal project, I imagined a scenario where a projectile with an initial velocity $x$ is affected by air resistance (drag) but not gravity, and I wanted to find out the distance it would ...
2
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1answer
77 views

Will the Earth's rotation someday be synchronized with its revolution around the Sun?

When will the earth act like the moon with regard to one side of the moon always facing the earth. Will the earth one day get locked in a rotational orbit that has one side of the planet facing the ...
1
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1answer
189 views

How to calculate escape velocity and orbital velocity for a cubular planet?

Given a planet that is a cube, how would one calculate the escape velocity and the orbital velocity? For a circular planet with an even distribution of mass (aka center of mass=center of volume) the ...
2
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2answers
74 views

Why is it easier to drop on to a downslope?

On a bicycle, why is it easier to land from a drop or jump on a slope going downwards than landing on a flat surface or on an upslope? I've already heard answers such as "because that's how a bike ...
0
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1answer
136 views

What is the potential and kinetic energy of the international space station?

I know it's possible to calculate, but what formulas would I use to be as accurate as possible? I'd like to see how it works for something big and high like that.
1
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1answer
91 views

What is the outward force on the Moon that makes it go in orbit rather that falling straight to the Earth? [duplicate]

So, we know that the gravity is responsible for pulling the Moon towards the Earth. But because it moves in an orbit, it makes me think that there must be a force that is causing the moon to travel in ...