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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Computing lengths for a rotating rod

I know how to assign dimensions to a profile that is under static loading - that is under Mechanics of Materials, I would agree on a beam section, calculate the maximum moment and use the elasticity ...
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0answers
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Dynamics particle motion around ellipse [closed]

For particle motion at constant speed around an ellipse with a major axis of 4 inches and a minor axis of 2 inches the ratio of the acceleration at pt. A to B is?
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4answers
70 views

What is the intuition behind “Net Work is Zero”?

I tried searching the answer to this all over the internet, but still cannot grasp this concept. So, when a book is being lifted, let's say $25 meters$ with a mass of $4kg$, with constant speed. I ...
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2answers
23 views

Does the effect change if a continuing and constant force acts upon a mass?

If a continuing and constant force $F$ acts upon a body with the mass $m$, does the power (work per unit time) increase over time? It would mean that the converted energy per time unit increases. Is ...
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2answers
59 views

Playing catch in space?

I was thinking about this on the bus (exam this week :P). What would happen if two people played catch in outer space? Lets say person A and B are in space at rest, A throws a mass m at B, what ...
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2answers
208 views

Can very large objects have a gravitational moment?

I was reading this answer about center of gravity vs. center of mass and it stated: Consider the Sears Tower. Its CG is about 1 millimeter below its CM. The reason why is because the base of the ...
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1answer
31 views

A sailboat and wind, to find $v(t)$

Consider a sailboat of mass $m$ that lies on still water. A wind blows the sailboat with velocity $v_w$ perpendicular to the sailboat. If the boat has a sail with area $A$, and the air density is ...
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2answers
80 views

Ratio of the magnitude of the normal force to the magnitude of the gravitational force? [closed]

I'm working through some practice problems in preparation for my physics final and ran into one that I'm not sure how to do. A mass is released from rest from the edge of a large hemispherical, ...
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1answer
53 views

Classical Mechanics - Potential Energy Function [closed]

Question The potential energy function of a particle of mass $m$ is: $$V(x) = \frac{cx}{x^2+a^2}$$ where c and a are positive constants. Qualitatively sketch $V$ as a function of $x$. Find two ...
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3answers
50 views

Force on a solid cylinder that is rolling on an accelerating block

Given: $m,R,I=mR^2/2, F,M$ and no traction between $B_2$ and the ground find $a_1, a_2$ (the accelerations of the CMs of $B_1$ and $B_2$ respectively).$B_1$ rolls on $B_2$ without sliding due to ...
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0answers
13 views

Spinning top don't fall and stationary one can't stay upright [duplicate]

Why a spinning top do not fall but a stationary one falls. What kind of law is governing it.
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2answers
895 views

What is the cause for the validity of Newton's third law?

What, specifically, causes newton's third law? For instance, if I push on a wall, why is it that I experience a force in the opposite direction? I seem to vaguely understand that is has something ...
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1answer
53 views

Why does the water rise upwards when the bottle fall down with accleretion $>>g$?

When a medium-sized bottle filled with water quarterly falls from a height with acceleration $g$, the water remains calm. But when it falls with acceleration $>>g$, the water abruptly rises up ...
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2answers
49 views

Why is there conservation of kinetic energy in elastic collision and not in inelastic collision?

Why is there conservation of kinetic energy in elastic collision and not in inelastic collision? What would be the difference that lead to conservation of kinetic energy in elastic collision and not ...
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1answer
33 views

Why a two wheeler is not pulled down by gravity while moving [duplicate]

As for every two wheeler the centre of mass will be much closer to earth in leaning position than in standing. but while moving it doesn't fall (lean).what kind of forces are preventing the falling ...
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0answers
143 views

how much force is necessary to move a 3368# airplane?

I have an airplane on tricycle gear (nosewheel and 2 main wheels under the wing). Sometimes I need to move it back and forth in the parking area. How much force must I apply to move it? The reason ...
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1answer
17 views

Period of swinging incomplete hula-hoop

I was working on a problem where I had to calculate the period of a swinging incomplete hula-hoop given its center of mass and radius. It only swings with very small amplitude so I considered the ...
2
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2answers
39 views

Does constant velocity of center of mass imply linear momentum is conserved?

I know that if momentum is conserved for a system, you can derive that the velocity of the center of mass of that system is constant. I was wondering if the second condition also implies the first: if ...
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2answers
114 views

Mass particle trajectory on a sphere

So, I am trying to simulate mass particle motion on the outer surface of sphere using cartesian coordinates. Let's conclude just a gravity and frictionless movement. Sphere $x^2 + y^2 + z^2 = 1$, ...
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4answers
3k views

What's the difference between centre of mass & centre of gravity for massive bodies?

My book says: For most of the small objects, both are same. But for mammoth ones, they are really different ones. And in a gravity-less environment, COG is absent; COM still exists. Ok, what's ...
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0answers
8 views

Is solving Verlet constraints parallelizable? [migrated]

I am a computer science student and I came across the Verlet Cloth simulation. An implementation is here. I was interested in how such computation would lend itself to parallelization. The problem ...
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0answers
51 views

Trying to modify the Tsiolkovsky rocket equation for the real world

Everyone knows about the famous Tsiolkovsky rocket equation. However, he formulated the equation neglecting many things. So, here, I am trying to find the real equation. My thinkings: Suppose, the ...
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7answers
3k views

Ball flying towards me or me flying towards ball

Suppose a ball is flying towards me at a speed of 10m/s and that, on impact, I feel "x" amount of pain. If, instead, it was me flying towards the ball at the same speed, with all other conditions ...
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1answer
28 views

Frictional force require to balance leaning sticks

Here is the question (from Morin's Introduction to Classical Mechanics book): One stick leans on another as shown in Fig. 2.21. A right angle is formed where they meet, and the right stick makes ...
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1answer
31 views

Minimizing a damping constant in order to minimize the amplitude of oscillations

How can I determine the damping coefficient that minimizes the amplitude of vibrations? This is an extension of Coupled ODEs that model a quad rotor \begin{align} ...
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3answers
62 views

Intuition and difference between centrifugal force & Coriolis force?

My book says that when a frame rotates uniformly, pseudo/fictitious force must be taken to count. This is centrifugal force. Also, while Googling, I found another pseudo force Coriolis force. ...
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1answer
131 views

Understanding of the $m v^2/2$ formula for kinetic energy

I have some problem to intuitively understand why the kinetic energy grows quadratically with the velocity (at least in non-relativistic case). Assume the following experiment: we launch an unmanned ...
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3answers
47 views

Finding minimum force to hold a particle in equilibrium [closed]

A particle of mass $m$ is suspended from a point A on a vertical wall by means of a light inextensible string of length $b$. Find the magnitude and direction of the minumum force $\boldsymbol P$ ...
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2answers
42 views

Flipping a bottle

I tried to do this experiment recently at school and my house. I started the experiment by having three same type of bottles with the labels A,B and C. Bottle A has been fully filled with water, ...
3
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1answer
71 views

Limits of A Mechanical Processor [closed]

Is it possible to build an electromechanical processor at high speed and capacity, with the same functionality as of today's modern microprocessors consisting of millions of transistors? I mean, ...
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2answers
75 views

Why do these two derivations of the formula for impulse contradict?

I was trying to derive $I = F\Delta T$ from $p = mv$. First I converted $v = at$: $$\begin{align} p &= mv \\ p &= m \times at \\ p &= ma \times t \\ p &= Ft \\ \Delta p &= F ...
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1answer
22 views

Torque on shaft

Consider a generator which supply power using a shaft to a turbine. The torque applied on shaft by generator is $T$. As the shaft has constant angular velocity the turbine should also be applying ...
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2answers
47 views

How to check if a system is in SHM in two spring systems?

I must determine if the system (a) is in SHM. I must arrive to the conclusion that there is a linear restoring force such that $a=-w^2x$. The solution's manual affirms that according to Newton's ...
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4answers
151 views

Why is $M\frac{dv}{dt} = v_{rel} .\frac{dm}{dt}$ correct and $(M - dm)\frac{dv}{dt} = v_{rel} .\frac{dm}{dt}$ wrong?

Newton's 2nd law of motion can't be applied for mass-varying systems. Another force, known as Thrust must come to play. It can be measured using law of conservation of linear momentum. ...
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1answer
37 views

How do I incorporate friction and mass when analyzing spring motion?

Problem 12 of section B of this PDF file reads Two springs with spring constant k1 and k2 are attached to a body of mass (m) in two different configurations in 2 cases (A and B) as shown. ...
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1answer
32 views

Problem on coefficients of friction? [closed]

How to approach problems where both coefficients of static and kinetic friction are given? Like in this: A 42 kg slab rests on a friction-less floor. A 9.7 kg block rests on top of the slab, ...
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2answers
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Why isn't there a net force when two rods touch each other?

This is a problem from Beer and Johnston's Mechanics of Materials (Amazon link). There's a problem in which there are two rods of different material, area, and length. The rods are fixed to walls, ...
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2answers
25 views

Prevent a box from tipping over: height of CG?

I'm on a problem that can be simplified in the following way: A box is placed on a horizontal plane, and is pinned to the ground on one side only such that it can tip over that side. Given a ...
3
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1answer
82 views

Waves and Newton's Third Law

I'm a really newbie in Physics trying to understand a bit about waves. Firstly, i'm using the Wikipedia's definition of wave , that is, as energy traveling through a medium/space without ...
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2answers
42 views

The principles of statics without force

I'm a student of civil engineering and now my course is covering the basics of statics, such as the equations of equilibrium, etc. Trying to get a better basis on the subject, I started to search on ...
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1answer
28 views

Newtonian Mechanics Cart Problem (Formula Derivation) [closed]

So I have a problem that reads: You exert a force of a known magnitude F on a grocery cart of total mass m. The force you exert on the cart points at an angle θ below the horizontal. If the cart ...
8
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7answers
538 views

Newton's third law and punching a glass or a feather

According to Newton's third law, action force equals reaction force in terms of magnitude. When I punch a glass, the glass punches me back. If I exert a greater force on the glass, it will break. ...
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1answer
27 views

Finding the moment of inertia of a lever [duplicate]

I am required to find the moment of inertia of the lever for a project in physics. This is my attempt: Please note that we have not been taught this yet in class so i have not been taught this ...
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2answers
54 views

Is this a correct understanding of circular motion?

We say an object experienced uniform circular motion iff it moves in a circle of constant radius, with constant angular velocity. To experience uniform circular motion, must the net force on the ...
3
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2answers
91 views

Introducing angular momentum for the first time to a class

What is the best way to introduce the notion of angular momentum to a class without making it appear an unnecessary and artificial construction?
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1answer
25 views

Enstrophy and energy spectral density of vorticity

I'm processing some flow field data obtained by PIV for a turbulent jet with the intention of using the energy spectral density (ESD) function to say something about the processes going on. I'm ...
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1answer
28 views

Why, in a car taking a sloped curve, friction is perpendicular to the car

In solving the problem we usuallly use the friction as the centripetal force, but I could never understood how is this possible. I understand that if a car is making a circular motion, some ...
4
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4answers
210 views

Why does a spring fixed to a wall have PE and not KE?

As many books,including mine (Principles of Physics by Resnick and Halliday) introduce, I also will present my example like this: Let there be a spring of negligible mass attached on one side ...
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2answers
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Calculating the force required to lift a weight with a screw

I am trying to learn physics by myself as I do not have a good teacher at school. I've been reading Feynman Lectures on Physics and I can't figure out how he found out this number. Here is an excerpt ...
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0answers
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Pulling fabric in a saddle shape tight with a spring

Jokingly a friend and I thought of a way to suspend a tarp-like material over my porch, very similar to they way a trampoline is sprung. However, this fabric is a rectangle and fits over arches. My ...