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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Static as opposed to Kinetic Friction in Rolling Motion

During analysis of rolling motion, why do we consider coefficient of friction as that of static friction and not kinetic friction?
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Velocity in a turning reference frame

I often see the relation that $\vec v=\vec v_0+ \vec \omega \times \vec r$ in a turning reference frame, but where does it actually come from and how do I arrive at the acceleration being $$\vec ...
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1answer
333 views

Newtons Cannon ball problem [closed]

Let's I have a Newton's Cannon ball of 15 kg and want to fire so it will round the earth and back to me. My query is which law can evaluate the speed that cannon ball will revolve round the sun ...
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1answer
155 views

Understanding Kepler's problem

I wanted to know a few things about elliptical motion, that I do not understand so far. Let's imagine that we have an attractive gravitational two body problem where both bodies carry out elliptical ...
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301 views

How to reconcile the two definitions of work? (mechanical and thermodynamical)

When studying classical mechanics, work is defined as: $W_M=\int F_{tot} \hspace{2 mm} dx$. However, for thermodynamics, work is defined as: $W_T=\int -F_{ext} \hspace{2 mm} dx$. I'm having trouble ...
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135 views

Simple pendulum and planet mass [closed]

A simple pendulum, $20cm$ in length, has the period of $2.7s$ on a certain planet. Find the mass of the planet if its diameter is $18000km$. $G=6.67\times10^{-11}Nm^2/kg^2 $ I have no idea how to get ...
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216 views

Forces involved in a climbing jet aircraft

I have a problem with which I need help. The question is: A jet aircraft is climbing at an angle of 45° above the horizontal and is accelerating at 4.5m/s2. What is the total force that the cockpit ...
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4answers
331 views

Action Reaction when I pushing a trolley?

I tried to explain how those force work but I can hardly figure it out. I exerted a force on the trolley and there will be a force on trolley on me as well. This is the newton's third law. But why the ...
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1answer
498 views

Bouncing ball simulation computer science

In my Computer science class I was given a problem where I have to simulate a bouncing ball using "real physics". I have been trying to find a equation that will simulate the height of the bounce ...
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1answer
117 views

Two masses on rope spinning around

Two balls of the same mass $m$ are connected to each other with rope of length $l$. One of the balls is also connected to the ceiling with a rope of the same length $l$. The balls are spinning ...
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147 views

Derivation of Universal Variables

Does anyone know of link to the derivation of the Universal Variables? This is in regards to Kepler's equations. The Wikipedia link didn't have enough information for me, and the Colorado page ...
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1answer
208 views

A block, a string and Newton's third law

So this is a general force diagram of the system shown. My question is, according to the third law, if the block is exerting a force of magnitude mg on the thread in the down direction, then the ...
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0answers
38 views

Delivered/Reflected Power by Drive on a Hamiltonian System

Imagine a SHO with a drive F(t). (or in general a Hamiltonian system) What is the power delivered to the system and can we talk about the power reflected? is i am imagining say a MW oscillator ...
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2answers
188 views

What is the sensation by man carrying a water bucker with an object floating in it? [closed]

A man is carrying a bucket with water. If a object is kept in it which floats in water, man will feel 1) heavier 2) lighter 3) none I think when the body floats its weight is balanced by upthrust ...
3
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2answers
211 views

Extension to continuous in proofs of rigid body mechanics

I'm studying rigid body mechanics and I've seen several proofs of properties related to total angular momentum, kinetic energy, etc. that all regard discrete set of points. For example, to show that ...
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456 views

No closed orbits for a Newtonian gravitational field in 4 spatial dimensions

We are supposed to show that orbits in 4D are not closed. Therefore I derived a Lagrangian in hyperspherical coordinates $$L=\frac{m}{2}(\dot{r}^2+\sin^2(\gamma)(\sin^2(\theta)r^2 \dot{\phi}^2+r^2 ...
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3answers
484 views

How you feel in outer space vs. orbit?

I understand that when someone is in low earth orbit, the "pull" of their inertia is equal to the pull of gravity. However, the force of gravity is still acting on them. However, if they are in outer ...
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2answers
222 views

Frictional Forces

In the figure, blocks A and B have weights of 45 N and 23 N, respectively. (a) Determine the minimum weight of block C to keep A from sliding if μs between A and the table is 0.21. (b) Block C ...
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What is the physical significance of the off-diagonal moment of inertia matrix elements?

The tensor of moment of inertia contains six off-diagonal matrix elements, which vanishes if we choose the principle axis of the rotating rigid body and the components of the angular momentum vector ...
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Velocity of an object undergoing homogenous acceleration

So I was considering the following problem within the context of Special Relativity: Given an object O, with initial velocity v, undergoing constant acceleration at a rate of a, I want to express the ...
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8answers
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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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1answer
368 views

Friction force and contact area [duplicate]

It's usually stated that the friction force is independent of the area of contact (Amontons' Second Law). I've always thought that this shouldn't be true, because the atraction between molecules ...
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4answers
546 views

How can acceleration $a$ be zero when applied force $F$ is non-zero?

An object is at rest and stays at rest, but an attached rope pulls with increasing force. What is the acceleration? The correct solution is that acceleration is constant and 0. Obviously $a= dv/dt ...
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2answers
315 views

Rotating spring system: Is my intuition correct?

Consider a solid spherical object of uniform density that is rotating on an axis A1. Perpendicular to that axis one can draw another line that passes through the sphere. On this axis, on both sides of ...
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283 views

Newton's First Law of Motion; Empirical Aspects

Newton's first law states that in an inertial frame, a body at rest continues to be at rest, and a body in constant rectilinear motion continues its motion, unless an external force is applied upon ...
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2answers
353 views

Why don't the components of these forces add up correctly? [closed]

In the arrangement as shown in the figure below, the ends P and Q of an inextensible string move downwards with uniform speed $u$. Pulleys A and B are fixed. Mass $M$ moves upward with a speed: ...
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Can one of Newton's Laws of motion be derived from other Newton's Laws of motion?

Can one derive Newton's second and third laws from the first law or first and third laws from the second law or first and second laws from the third law I think Newton's laws of motions are ...
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1answer
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Question about weightlessness

Let us consider +Y as upward and -Y axis as downward. So the acceleration that works these objects is always $-g$. For the first picture, if the lift is going upward with acceleration $a$, then ...
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How to design a deliberately biased coin?

For demonstrating basic probability concepts, it would be nice to have a coin-like object that lands heads/tails not in 50/50% ratio, but biased in a way that can be revealed in a short experiment. ...
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1answer
311 views

The quickest 6-3 play in baseball: to bounce or not to bounce?

What's the quickest way the get the ball (say from shortstop) into the first-baseman's glove, given some fixed initial (throwing) speed? Directly or with one bounce? I'm fairly sure that the answer ...
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599 views

Huge buildings affect Earth's rotation?

Does constructing huge buildings affect the rotation of the Earth, similar to skater whose angular rotation increases when her arms are closed comparatively than open?
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1answer
263 views

Question on friction [closed]

Please look at the figure carefully. The question is written, and one has to match the two columns 1 and 2 given under "choices and explanation". Please tell me if I am really wrong, i.e. would you ...
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2answers
384 views

How to calculate air resistance of penny dropped from Empire State Building?

If a penny is dropped from the Empire State Building, then its speed, without taking air resistance into consideration, is $\sqrt{\left(32\frac{\textrm{ft}}{\textrm{s}^2}\right)(1454\textrm{ ...
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4answers
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Short-duration forces

In circular motion, it is said that the centripetal force acts only for a very very short period of time, hence is able to only change the direction but not magnitude of the velocity. Similarly in a ...
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Finding the force of an object? [closed]

Sorry if my initial question was seen as a "homework question" but I don't really know how to go about asking this type of question. I have a feeling I have to use Newtons law but there is no ...
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3answers
346 views

Where does the extra equation come from to determine the forces from an object on a table?

I have a question about basic statics but somehow I cannot manage to find the answer on my own (btw, this is not a homework. It's been so many years since school for me...). The problem is very ...
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2answers
488 views

Will a spinning object come to rest?

Will a sphere spinning on its own axis come to rest given enough time, provided no other forces act upon it? I know that if you have two spinning spheres in the depths of space and orbiting each ...
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4answers
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Terminal velocity of all falling objects is same?

Ideally 2 objects of different mass and weight will hit the floor at same time because they face same gravitational pull and accelerate. Will the terminal velocity of both objects be same also? and ...
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3answers
173 views

Violation of Newton's 3rd law

I'm just expressing my guess. Let two particles A and B experiences forces $F_1$ and -$F_2$ between them and let guess also there are two observer, one is stationary and other is moving with ...
6
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1answer
137 views

Why does this screwdriver roll in a curved trajectory?

I am trying my level best to give this screwdriver a horizontal push only, but it is going in a circular path. I thought of uneven friction due to non-uniform normal reaction...what do you think? I ...
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1answer
372 views

1D Kinematics - Relative Motion involving non-inertial frames of reference

I recently came across a question involving non-inertial frames of reference. I didn't quite understand the way it had been solved due to some conceptual confusion regarding certain deductions made to ...
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150 views

Does the slip-stick phenomenon have any application?

The slip-stick phenomenon is present all around us, be it the noise of car breaks or in earthquakes. But does it have any real-life application?
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1answer
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How does tension apply torque on a pulley?

How is tension in a string able to apply torque on a pulley? How does string itself able to apply a force on pulley? What is happening inside the pulley? The pulley has a mass $m$ and is a disc.
2
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1answer
925 views

Escape velocity for hydrogen molecules

The question: At what temperature is the RMS speed of Hydrogen molecules equal to the escape speed from the earth's surface? Values of radius of earth($r$) and gas constant $R$ has been supplied ...
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2answers
377 views

How large can planets or moons appear?

In many artistic impressions or movies there are pictures or scenes where the sky is filled with an enormous moon (as seen from a planet) or vice versa. I wonder if there is an upper limit to the ...
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1answer
432 views

Pulley system with rope

Two masses $m_1$ and $m_2$ are connected through a weighty, uniform and an unstretchable rope of length $L$. The surface is frictionless. Masses of the objects are $m_1=m$, $m_2=\frac{2}{3}m$, mass ...
2
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2answers
143 views

Intuition contradicting answer for calculating pressure

I have a cylindrical container say of some base area $A$. The atmospheric pressure is $P_0$. The cylinder is moved at an acceleration $a$ horizontally right. I need to find which base would have to ...
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314 views

Momentum, Impulse and Newton's Second Law of Motion

Newton formulated his Second Law as such: $$\sum{\vec{F}} = \frac{\delta \vec{p}}{\delta t}$$ and of course, $\vec{p} = m \vec{v}$. Why is it that if the net force $\sum \vec{F}$ is constant (which ...
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1answer
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How do determine the equation of motion of slinky?

I'm trying to analyze the forces exerted to slinky. First, I've divided both ends. The red vector is the force exerted by slinky itself, and the green vector is gravitational force. Force exerted ...
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1answer
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Problem with a rotating frame of reference on the South pole

Consider this problem: A high-speed train is traveling at a constant 150 m/s (about 300 mph) on a straight horizontal track across the south pole. Find the angle between a plumb line suspended ...