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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Why can't we put an object anywhere in the earth's orbit around the sun instead of Lagrangian points?

If we place an object in the earth's orbit around the sun, it should have the same orbital period right? For example, what would be the behavior of an object in orbit at point A1? It is at the ...
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1answer
51 views

How does paddling in the water help a boat move forward?

The way I've seen it explained is like this: it all has to do with Newton's third law. However, the "equal and opposite" reaction predicted by the third law acts on the paddle - which is not ...
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31 views

What is the equation for the position of a falling body as a function of time? [duplicate]

I know that near the surface of the earth a projectile's position follows a parabolic curve in function of time because the acceleration is constant (about 9.8 m/s2). However, acceleration ...
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4answers
86 views

Would running along Earth's Surface at escape velocity cause you to get out of the Earth's gravitational pull? [duplicate]

If one were to run/drive/fly along the earth's surface (by this I mean tangential to the Earth) at escape velocity (about 7 miles per second), would that person escape the gravitational pull? If not, ...
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1answer
52 views

If a disc is rolling on a surface, how do you verify that no slip occurs? [closed]

If I have the values for the coefficient of static friction (0.1) and all the other variables, how do I verify that no slip occurs?
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1answer
72 views

How does friction affect the motion of a pendulum?

I would like to know what is the difference in the equation of motion of a pendulum in the presence or the absence of frictional forces. And how this translates to the solution of those equations?
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3answers
51 views

what is the difference between these two systems? [closed]

what is the difference between these two pulley systems when calculating the angular acceleration if the moment of inertia and radius is the same?
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1answer
50 views

Does the rotational form of Newton's second law always hold?

Does the equation, $$\vec \tau=I\vec \alpha$$ (rotational form of the second law) always hold? If not, in what conditions does it hold true?
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0answers
52 views

Rotating rigid rod in empty space [duplicate]

To begin, we assume there is a rigid rod in empty space which has no rotation with respect to the fixed stars. The frame of the rod is now an inertial reference frame, say $F$. 1) The rod now has a ...
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1answer
38 views

Dependence of tension (considering a pulley system) on the mass of loads

Consider the diagram below All circles are pulleys, which are fixed at the ceiling. M represents an engine (with a certain power) that is pulling the cable. C and D are weights. The acceleration of ...
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1answer
76 views

A cruise ship bumping against a lock gate [closed]

For my project, I need to create a lock gate which will be used for the Panama Canal. One of the many thing my teacher said, was that for the design of the lock gate, the gate should not fail when it ...
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1answer
63 views

How do I show that the total energy of a particle moving in an electrostatic field is constant?

Basically the Lorentz force says that: $$F=qE+qv × B$$ I am asked to show that if a particle moves in an electrostatic field $$E= - ∇V(x,y,z)$$ and ANY magnetic field, then the energy: ...
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36 views

Does frequency of a vibration wave of a cantilever depend on its deflection?

cantilever= a beam fixed at one end only deflection is the initial displacement of the free end. the beam is let go when the free end reached its position it will vibrate, does the frequency of ...
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0answers
24 views

Standing waves arbitary frequency

Suppose I have a string that is fixed rigidly at one end. Now when I start making wave, it will get reflected and should lead to standing waves (Mathematically and by visualization), but then we have ...
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1answer
96 views

Oscillation of non-uniform plank on parallel springs

A plank of length $l$ and mass $m$ is placed on two parallel springs, each with spring constant $k$ and equidistant from the plank's horizontal center of gravity. When the plank is displaced from it's ...
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0answers
12 views

Power Generation Via 2 connected objects below distinct orbits

As an example: Large weight A sits just below Earth's orbit Large weight B sits just below Moon's orbit A, B are connected by sufficiently strong material (may not exist, and if so how much ...
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4answers
189 views

Why does Torque exist?

Specifically, why does force increase with the moment arm? What about making a perpendicular force farther away from the axis of rotation increases it? How does the moment arm cause that?
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4answers
204 views

Is it correct to say Newtonian mechanics is a subset of Quantum mechanics?

I grew up in a three dimensional (3D) reality described quite well by Newtonian mechanics as opposed to the reality described by Quantum mechanics. That is I could go to bed at night without worrying ...
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2answers
47 views

Simple harmonic motion..direction of acceleration

To solve questions about simple harmonic motion, my book says $\ddot{x}$ (i.e. acceleration) is in the direction of increasing $x$, i.e. away from equilibrium. I don't understand why is this so, since ...
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1answer
88 views

What's the distance between the center of mass and geometrical center of Earth? [closed]

With a good approach we can say that they are identical. But how accurate is this approach? Since Earth is not homogeneous there must be (can be) some difference. In other words I'm asking if Earth ...
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4answers
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Is there an underlying physical reason why the Coriolis force is similar to the magnetic component of the Lorentz force?

I couldn't help but notice that the expression for the magnetic component of the Lorentz force, $$\mathbf F = q\,\mathbf v \times \mathbf B\,,$$ is very similar in its mathematical form to the ...
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2answers
123 views

Why is this specific definition of acceleration used in deriving a general equation for kinetic energy?

$$\sum_{i=0}^n m_i v_i$$ as well as $$\frac{1}{2}\sum_{i=1}^n m_i v^2_i$$ Have been proved to be conserved by Newton & Leibniz, respectively. (http://en.wikipedia.org/wiki/Vis_viva) I don't ...
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67 views

Sliding blocks problem

My first post here, so I apologize if this is duplicated elsewhere. It IS a "homework" problem, but it's public domain, a posted exam with answers... ...
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1answer
58 views

Period of simple pendulum accelerated horizontally

I'm confused about simple pendulum problems where the pendulum is accelerated horizontally of anyway not vertically with acceleration $\vec{A}$. $m\vec{g} + \vec{T}-m \vec{A} =m \vec{a}$ So ...
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Throwing a Football. Is it truly parabolic?

Driving into work, I started thinking about the arc of something being thrown and was puzzled about how gravity's affect is squared per second for falling bodies. Intuitively that implies the shape ...
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2answers
105 views

Forces on wheels in an accelerating vehicle

Assume that a motorcycle of mass $m$ has two wheels that are equidistant from its centre i.e the force on each wheel is $mg/2$. If the motorcycle accelerates forward, will the two forces on each ...
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1answer
88 views

Fallacious derivation of the rocket equation

Consider a rocket in free space of initial mass (including fuel) of $m_0$ using up/ejecting fuel at a constant rate $r$ (mass per time). That means that at time $t$ the rocket has mass $m=m_0-rt$. The ...
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7answers
401 views

Why is force a vector? (The Feynman Lectures)

A vector is a quantity that transforms just the way the coordinates transform under rotation (while a scalar remains invariant under rotation). In FLP, he says suppose $F$ is a vector and probably ...
3
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1answer
115 views

Effect of general relativity on Newton's second law

Let's say I have some object, like a long pole, that is 30 km long with non-zero mass $m$. One end is resting on the Earth's surface and it is sticking straight up, perpendicular to the surface. ...
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64 views

Derivations of Newton's laws?

I feel convinced that the mathematics behind newtons laws can be derived from Noether's symmetry theorems. The fact that displacement s can be described by a cartesian coordinate system with a ...
4
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1answer
81 views

Cylinder on an accelerated rough plane [duplicate]

The following figure shows a cylinder resting on a rough horizontal rug that is pulled out from under it with acceleration $a$ perpendicular to the axis of the cylinder. What is the motion of ...
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2answers
54 views

How can amplitudes be treated as vectors in Simple Harmonic motion?

The amplitudes of 2 SHM are scalors. When we combine the two SHM eq.(lying along the same line), the resultant expression becomes of amplitudes treated as vectors and the phase angle between them as ...
2
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1answer
51 views

Moment of Inertia of Square Lamina [closed]

I know how to compute this using an integral. However, I was told that I could derive this as well by placing 4 squares together of moment of inertia $$I=kmr^2$$ and derive it again but I'm not sure ...
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1answer
34 views

Solving an acrobat problem in 3 methods

A circus acrobat of mass $M$ leaps straight up with initial velocity $v_{0}$ from a trampoline. As he rises up, he takes a trained monkey of mass $m$ off a perch at a height $h$ above the trampoline. ...
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2answers
88 views

What formula do I use to calculate the force of impact of a falling object?

I am trying to calculate the force of impact of a falling object. I did my egg drop project. I dropped the egg from 10m with a mass of 126kg and with the velocity of 14.1 m/s. Which formula should I ...
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1answer
78 views

How can the work done by friction be positive? [closed]

I have this energy related problem that i cannot understand in this problem, I am required to find the velocity of the 4.8kg mass when it hits the ground. I easily solved this problem using newton's ...
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3answers
120 views

Resolving horizontal and vertical components on an inclined plane

Here is a very simple mechanics question related to inclined planes: We assume that the body is at equilibrium or at constant speed. To work out the force 'R', I resolve the 100N force due to ...
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2answers
86 views

Newton's third law & punching walls [closed]

N-law 3: if you punched a wall as hard and as you could, would it possible to retract your hand before the reaction from the wall could affect your hand less than if you wouldn't retract at all? ...
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1answer
56 views

A heavy chain with upper end falling with constant velocity

The most basic form of my question is: "Can the normal force from the ground be enough to let a chain's upper end fall at constant velocity?" I suspect the answer is no, but to elaborate, here is the ...
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3answers
87 views

Frictional Force of a Rolling Object

I'm not sure that I understand this problem: A spool of wire of mass 4.7kg and radius 0.99m is unwound under a constant wire tension 10N. Assume the spool is a uniform solid cylinder that rolls ...
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2answers
61 views

What does well defined parity mean

I'm reading a textbook (Physics of Quantum Mechanics by Binney) and it says that the ground state ket $\left\lvert 1 0 0 \right \rangle$ of the hydrogen atom has well defined (even) parity. What does ...
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1answer
160 views

Would a non-rotating Earth collapse on the Sun?

If the earth stopped rotating on its axis, would this influence its revolution motion? In particular, could it collapse on the sun? I ask this because on the one hand I thought the two degrees of ...
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2answers
60 views

Conservation of momentum for moving inclined plane

I'm confused about the conservation of momentum in problems involving inclined planes that moves. Consider an inclined plane free to move on the floor and a body on the edge, there is no friction at ...
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2answers
63 views

Condition for looping the loop

Consider a ball tied to a string and it is imparted a velocity we have studied that condition for looping the loop is that tension at the uppermost point must be zero, but why is this condition ...
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0answers
66 views

Moments of inertia of composite area - xaxis [closed]

struggling with this question. Got the a) ( y¯ = 3.79 in )but can't seem to get b) a) Locate the centroid y¯ of the composite area. b) Determine the moment of intertia of this area about the ...
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1answer
44 views

Reason behind Inertia

Has any physicist work on the reason behind Inertia? Why do we have inertia only during acceleration? No inertia during constant velocity.
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3answers
43 views

Why does work in the Work Energy Therom equal the Sum of the integral F*dr?

I am studying the work energy therom and I understand that 1/2(mv^2)=Wnet, however, I saw this picture below online. I understand the summation of the force times the change in distance. However, ...
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1answer
43 views

Will the Earth ever show synchronous rotation? Why and when?

In this answer to the question "why does the moon have the same rotation and revolution periods?", we read: The mass and speed of rotation of the Earth influence the moon in that some of its ...
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2answers
83 views

Elastic potential energy and equilibrium position when mass changes in vertical mass-spring system

I'm a bit stuck with this situation: Suppose that an object $A$ with mass M=8 kg at 10 mt above the floor falls from rest tied to an 2 mt elastic rope, which does not exert any force since $A$ falls 2 ...
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3answers
39 views

Role of forces in this collision?

Consider two identical objects of equal mass collide with eachother with equal opposing accelerations. Wouldn't the forces of the objects cancel each other resulting in the objects both comming to a ...