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.

learn more… | top users | synonyms (3)

1
vote
1answer
34 views

How is hemispherical shell any different from a semi-disc in terms of center of mass? [closed]

If we shift all the rings that make up the hemisphere parallel towards the center then it will build up two semi-disc .. But we know that We can also explain it by saying that if we take the shadow ...
0
votes
3answers
50 views

Physical interpretation of Coriolis terms in acceleration

Consider a reference frame which is rotating (for example on a carousel) and a steady inertial frame, with the same origin. $\vec{r}=\vec{r'}$ $\vec{v}=\vec{v'}+\vec{\Omega}\times\vec{r'}$ ...
3
votes
2answers
506 views

Is Newton second law covariant or invariant?

Is Newton second law covariant or invariant between two inertial frames, moving with uniform traslational motion with respect to each other? If it is invariant then, indipendently from the frame, ...
1
vote
3answers
75 views

Why charge is not a measure of inertia?

We know that mass is the measure of inertia of rest. Then why charge is not a measure of inertia? What causes the difference between charge and mass?
3
votes
3answers
198 views

Why is the definition of inertial mass circular?

On Wikipedia, the definition of inertial mass is: Inertial mass is the mass of an object measured by its resistance to acceleration. And, can be evaluated using $F = ma$, Newton's second ...
2
votes
4answers
85 views

Is torque necessary in rigid body mechanics? [duplicate]

Suppose we have a weightless, rigid rod fixed at one end, but free to swing at the other, where there is a mass $m$ attached. If we want to determine the tangential acceleration of the mass using ...
1
vote
2answers
151 views

Angle of a pendulum as an explicit function of time

What would be the solution for the angle $\varphi(t)$ and angular speed $\omega(t)$ on pendulum without the small angle approximation - not as differential, but as an explicit function of time? The ...
64
votes
3answers
3k views

Why do travelling waves continue after amplitude sum = 0?

My professor asked an interesting question at the end of the last class, but I can't figure out the answer. The question is this (recalled from memory): There are two travelling wave pulses moving in ...
1
vote
1answer
29 views

Help me understand this simple linear momentum [closed]

A 40.0-kg skateboarder on a 3.00-kg board is training with two 5.00-kg weights. Beginning from rest, she throws the weights horizontally, one at a time, from her board. The speed of each weight is ...
1
vote
0answers
29 views

Force acting on a pole which is fixed with friction [closed]

A uniform pole of weight 50kg is balanced in the vertical position. The length of the whole pole is 6m.the pole is fixed at point C on the ground.A force 500N is applied at B which is 2m from C. If ...
0
votes
1answer
64 views

Scenario where Newton's 3rd Law breaks down

In Kleppner and Kolenkow's Introduction to Classical Mechanics, it reads, One system that is particularly troublesome for our present formulation of Newtonian mechanics is the electromagnetic ...
3
votes
3answers
72 views

Understanding Feynman's argument about Stevinus

In the Feynman lectures vol 1, chapter 4, he mentioned a "Brilliant, clever" way of solving a problem named: A simple example is a smooth inclined plane which is, happily, a three-four-five ...
2
votes
3answers
293 views

Quantum mechanics of the electron in an atom vs. Gryzinski's free-fall atomic model [closed]

According to Heisenberg's Principle of uncertainty, you can not know the place and speed of a particle, at the same time. You only have probabilities of the estimate values. These probabilities forms ...
3
votes
4answers
291 views

Why do wheels spin?

I'm pretty sure this is probably a stupid question but it is annoying me a lot. In my physics textbook it says, cars move because the wheels exert a backward force on the ground and the ground exerts ...
0
votes
2answers
60 views

How does rocket thrust work?

I can't seem to find a specific answer to this anywhere. I understand that in a rocket there is a chemical reaction that causes gas particles to leave the rocket at high velocity. By Newton's third ...
0
votes
1answer
30 views

Why isn't the entire force we apply on two objects transmitted to the second object?

When we exert a force of X N on a box in contact with another identical box on a frictionless surface, the resultant force on both boxes is 0.5X N. My question is, why doesn't the first box push the ...
0
votes
0answers
23 views

How to predict the group velocity of the waves in the liquid?

The question appeard in the book. The phase velocity of the waves on the liquid surface is given by $$V_{ph}=\sqrt{\frac{2*\pi S}{\lambda \rho}} $$ where S is the surface tension and $\rho$ is the ...
3
votes
3answers
84 views

Car Crash Question… (Conservation of Momentum?) [duplicate]

Dumb car crash question. I think this is a conservation of momentum problem. In one scenario, two 4000 lb cars (car A and car B) each traveling at exactly 35 MPH in opposite directions have a ...
0
votes
3answers
769 views

How can planes land on a rotating Earth?

If the earth is rotating (e.g. at 1000km per hour, at the equator), how can planes safely land on a moving runway?
0
votes
0answers
21 views

Books on Celestial Mechanics [duplicate]

My background is mathematics. I would like to study celestial (not classical) mechanics and looking for an appropriate book. I found that somebody has already asked a similar question "How to learn ...
0
votes
3answers
47 views

Is “power to mass ratio” in fact independent to mass?

I was trying to find power to mass ratio of sun (work done per second at each unit mass at average), but I found the unit is quite straight: W=kg m^2 s^-3 Then ...
1
vote
1answer
31 views

Frequency of oscillator

We are given an undamped simple harmonic oscillator, and two positions $x_{1}, x_{2}$ with the corresponding velocities $v_{1}, v_{2}$. We want to find its frequency in terms of the $x_{i}$ and ...
0
votes
2answers
54 views

Why can some oscillations be modeled by Simple Harmonic Motion, while others cannot?

For some oscillators an increase in the driving amplitude changes the period (frequency) of the oscillation, but the simple harmonic oscillator does not predict this type of behavior. Why?
1
vote
1answer
35 views

How to find the direction of friction in rotation?

Suppose we have a spool which is plucked constantly from top with a force F. The spool is on a rough ground. We have to find the direction of friction, nd direction of motion of spool. ...
1
vote
1answer
35 views

Component of Component of a vector [duplicate]

NOTE : By perpendicular component of $\vec{F}$, I mean a vector which is a component of $\vec{F}$, but perpendicular to it. In the image above, the red vectors are a possible set of rectangular ...
6
votes
4answers
86 views

Newton third law and collinearity of forces

I have a doubt on the formulation of Newton third law. When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction ...
-1
votes
1answer
51 views

Law of conservation of energy and time [closed]

Consider the following in a space (with out any external influences like gravitation) Let say i have two identical bodies b1,b2 and i applied a force F on them to make them accelerate a. After t time ...
0
votes
1answer
52 views

Finding speed of an object on an inclined spring [closed]

question posed here: http://puu.sh/nV7rw/504a7be88a.jpg method: Conservation of energy $E_{{mech}_i} = E_{{mech}_f}$ $U_i + KE_i = U_f + KE_f$ $\frac{1}{2}{k}{x^2} + {mgh_i} + 0 = ...
0
votes
1answer
34 views

Optics of stationary waves

could anybody tell me how it Works if it comes to stationary waves created on the surface of water jet and optics? there are some crests and troughs which work like lenses, but if you have water jet, ...
0
votes
1answer
53 views

How to model analytical expression for spring constant $k$ for certain structure?

In the deflection of beam, I learned that $$ \delta y=\frac{FL^3}{3EI} $$ where $$ I=\frac{h^3w}{12} $$ Together they comprise $$ F=\frac{Eh^3w}{4L^3}\delta y $$ How do I apply to four beams? ...
0
votes
2answers
47 views

Wave intensity and superposition

Let us say we have 2 point sources of sound. My question is how do we consider the intensity to vary according to position? Let's say both have same amplitude, frequency and speed, just different ...
1
vote
1answer
67 views

Deriving a Schwarzschild radius using relativistic mass

Introduction I have shown below two different approaches to deriving the Schwarzschild radius. I know these are less rigorous than the derivation of the Schwarzschild solution however the ...
1
vote
2answers
56 views

What Feynman meant in description of reversible machine and levers

In chapter four of the part one of the lectures, he mentions: (..) A machine that we actually use can be, in a sense, almost reversible: that is, if it will lift the weight of three by lowering ...
2
votes
0answers
22 views

Pressure on a piston [closed]

There are 2 syringes X and Y connected to each other horizontally. If pressure in atmosphere (P) is 1x105 Nm-2 and the pressure we should apply on X to have the velocity when liquid come out is ...
0
votes
0answers
19 views

How to find positions in the equilibrium state of mass-spring system?

I've simulated 3D mass-spring system (mesh/network). First the system was in equilibrium state of it own (called state {A}). If I moved some of the masses in the system to the new positions, the ...
0
votes
1answer
37 views

Technique to Solve 2-Dimensional Linear Momentum Problem

Problem: After a completely inelastic collision, two objects of the same mass and initial speed stick together and move away at half their initial speed. Find the angle between their initial ...
1
vote
1answer
68 views

Patterns in falling viscous fluids

It is a common observation that honey(or any other viscous fluid),tends to overlap/coil/wind up as it reaches the rigid surface. There is this little bend near the pile-up. Why is this so? How does a ...
1
vote
1answer
42 views

Force of Gravity of a stationary object acting on another object moving through space

Story: I have x and y positions of a spaceship as it moves through space to some goal location at [1000, 700]. A record of its movement is given by: ...
1
vote
1answer
57 views

Mechanics of a falling cat [duplicate]

It is a general statement that cats tend to fall on their feet. How far is this is a valid statement? If I were to drop a cat from 50 meters height, feet up(hypothetically), would it still land on ...
0
votes
1answer
42 views

Instantaneous Velocity after bouncing off a wall

I have a ball, and I throw it at a wall as a projectile (assume that the ball's position the instant the journey begins is on level-ground). The ball hits the wall with a velocity that is at right ...
0
votes
1answer
31 views

How to compensate a top-heavy platform [closed]

I have a small four-wheeled platform weighing 1.3kg with a height of 30cm. Its center-of-mass is located at 75% of the height, making it a little top-heavy. I empirically measured the angle at which ...
1
vote
1answer
31 views

What decides distribution of momenta and energy in rigid collisions?

I recall in Highschool physics receiving a problem of the form "assume 2 spherical bodies" $P_1, P_2$ enter a collision where $P_1$ has momentum $m_1 V_1$ and $P_2$ has momentum $m_2 V_2$, both ...
3
votes
1answer
45 views

Conservation of Energy of two charged blocks connected by light spring

Two identical blocks resting on a frictionless, horizontal surface are connected by a light spring having a spring constant $k = 100 N/m$ and an unstretched length $L_i=0.400 m$. A charge $Q$ ...
0
votes
0answers
62 views

Unclear things about conservation of energy

I have started reading Feynman Lectures in Physics, First Volume, with absolutely no background in physics [*]. In the fourth chapter, conservation of energy, I am having difficulty understanding ...
1
vote
2answers
51 views

Dynamics: Forces in a closed system

I need help with the following question: There is painter in a crate which hangs alongside a building. When the painter pulls on the rope, the force he exerts on the floor of the crate is 300N. The ...
0
votes
0answers
35 views

Axial loaded bars problem

I completely disagree with the following calculations: Based on my understanding, there is no force either internal or external applied to the Green bar, so it should be 0N. The reaction (internal) ...
0
votes
2answers
61 views

Is polar coordinates frame non-inertial?

Consider the acceleration expressed in polar coordinates. $ \left( \ddot r - r\dot\varphi^2 \right) \hat{\mathbf r} + \left( r\ddot\varphi + 2\dot r \dot\varphi \right) \hat{\boldsymbol{\varphi}} ...
1
vote
1answer
37 views

In rotating frames, particles do not travel at constant velocity?

If we measure a particle's trajectory in a rotating frame of reference as $\vec x=\vec x(t)$, then $\frac{d^2\vec x}{dt^2}=0$ could be zero? I'm trying to explain why the Newton's first law of ...
0
votes
1answer
31 views

Explanation of a Mechanical Situation [closed]

The box sitting on the table top has some mass $m$ (I would refer to the weight of the box just as $\mathbf{W}$), and its net acceleration which I call $\mathbf{a}$ is zero, for the time being. This ...
0
votes
1answer
25 views

Structure of force table

In school, they asked us to do a force table and to search about it on internet to know what to do. The problem is that I searched for hours but I didn't understand the concept 100% since I am not ...