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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2answers
70 views

What is the main key to distinguish the oscillator from the two system?

Let a circular hoops of radius $r$, is hanging on nails in a wall. Can I consider this as simple pendulum so the frequency $\omega = \sqrt{\frac{g}{L}}$? On the other hand If I consider that ...
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3answers
173 views

Doubt on a question from Newton's laws of motion

We(me and my classmates) had completed a chapter on Newton's Laws of Motion. Now this question pops up: A cricket ball of mass $70\,\mathrm{g}$ moving with a velocity of $0.5\,\mathrm{m/s}$ is ...
2
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2answers
156 views

Gravitational Null Point between Earth and Moon

I need help finding the gravitational null point point between the Earth and the Moon, the point beyond which you start falling towards Moon. I am having difficulty in taking into account the orbiting ...
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0answers
141 views

Why would the relationship between period and mass be important to you in a Simple Harmonic motion?

My lab's teacher always asks us why we're there at lab before the class starts. We already know the variables we're supposed to measure, so we frequently say (We used to say): "We want to find out the ...
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1answer
101 views

A question on Rolly polly dolls

I was reading on rolly-polly dolls when the following questions crept into my mind How exactly does center of gravity play a role which helps rolly-polly doll to stand up on its own? Can a ...
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1answer
84 views

Gravity Relative to Mass?

Why is it that, in basic physics, it is taught that the acceleration of gravity is the same for objects of any mass (at a constant distance from earth)? Why then is the acceleration of gravity ...
-2
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1answer
71 views

Would the system exhibit periodic motion? [closed]

A mass moving in one dimension has a potential energy given by :- $$V(x)=\frac{k_1}{2}x^2+\frac{k_{2}}{x}$$ where $k_1$ and $k_2$ are positive constants and $x>0$. Is this system exhibiting ...
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1answer
225 views

Momentum is conserved without the application of Newton's third law in cases of non-rigid bodies like spring

Let a spring be attached with a block moving with $v_1$; when another block with velocity $v_2(v_2 \gt v_1)$ hits the spring from the rear end, the spring gets compressed until both the blocks have ...
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1answer
94 views

What is meant by saying the work done by a conservative force is -(change in PE)?

I read through all related questions, and they are almost the same, but I still didn't understand this and so am asking again. What is meant when we say that the work done by conservative force is = ...
2
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2answers
98 views

Is there any loss or gain of information if a physics law is changed from one form to another? [closed]

Is there any loss or gain of information if a physics law is changed from one form to another such that the parameter appearing in them is changed from vector to a scalar? For example, consider the ...
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0answers
54 views

Third law of motion when action and reaction are separated by some time

For every action there is an equal and opposite reaction. I have used this law only when bodies are in contact with each other which means for every action reaction is produced at same instant of ...
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0answers
65 views

How can I approximate Jacobian Elliptic Functions in terms of basic integrable functions for the SO(3) rotation of a rigid body?

So, the rotation of a 3d body can be described with Euler's equations of motion giving the rotational velocity in components along the principal axes of inertia. As showed in f.ex. this paper, ...
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2answers
448 views

How is Chasles' Theorem, that any rigid displacement can be produced by translating along a line and then rotating about the same line, true?

Chasles' Theorem in its strong form says: The most general rigid body displacement can be produced by a translation along a line (called its screw axis) followed (or preceded) by a rotation about ...
1
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1answer
45 views

How to determine the acceleration and position as a function of time

An object is losing mass at a rate k in kg/s. The object is acted on by a force F. Determine the acceleration and position as a function of time. I know the answer for the position function is ...
2
votes
2answers
269 views

Why does, at one time, tension balances the weight but at the other time don't balance it?

Everyone is accustomed to many set-ups of Atwood machine; sometimes the question asks about acceleration of the blocks or so; sometimes they ask about tension etcetera. But one thing I couldn't ...
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0answers
63 views

Probability density function of simple Mass-Spring system

We know that after long run of simple mass-spring system, there should be a probability of finding the mass at certain points between -A and A.. Obviously in probability of finding the particle near A ...
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4answers
197 views

Why is force called the rate of change of momentum? [closed]

Why is force called the rate of change of momentum? If I push a wall I do exert a force but there is no movement; so is there force acting on the wall?
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1answer
156 views

Free-fall with linear drag

The standard first-course free-fall with linear drag situation posits a particle falling with a constant acceleration (typically due to approximation of gravity), but with a retarding force that is ...
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0answers
101 views

What are the kinetic energies inside a car and a train

There are two boxes of equal mass (50 Kg each). Box A is a top of moving car (1000 Kg) and Box B is a top of moving train (10 000 Kg). Both car and train are moving at same speed and velocity (80 ...
4
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1answer
108 views

Why & how do bodies attached by extensible strings move with common acceleration?

From the very beginning of my journey of physics, I have been taught that while dealing problems having attachment of one body to another mass , if the string connecting the bodies be ...
1
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1answer
147 views

Eigenvector of spin half particle in applied magnetic field at angle

I am very new to this field of physics so sorry if this is basic. I was recently trying understand how you go about calculating energy splits of electrons in applied fields. I understand that given a ...
-3
votes
2answers
99 views

Why the bob leaves the circular path when tension in the string becomes zero [duplicate]

In vertical circular motion of a bob attached with a string, we say that the bob leaves the circular path when tension in the string becomes zero. But even when tension becomes zero there's ...
2
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2answers
138 views

Total energy of a circular orbit

A particle of mass $M$ moves in a circular orbit of radius $r$ around a fixed point under the influence of an attractive force $F=K/r^3$, where $K$ is a constant. If the potential energy of the ...
1
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1answer
134 views

Momentum and collisions [closed]

Two blocks of masses $m_1$ and $m_2$ connected by a spring of force constant $k$.The block $m_1$ is suddenly given a velocity $v_1$. Find the work done by the spring on both the blocks when it has ...
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1answer
75 views

Why is drag neglected while dealing with kinematic problems?

Why is drag neglected while dealing with kinematic problems? While dealing with problems related to finding velocity, acceleration and other kinematic problems, it is mentioned to "neglect drag". ...
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2answers
76 views

From Newtonian systems to Lagrange mechanics using Euler - Lagrange equations [closed]

I am reading some notions about Lagrangian Mechanics from Holm's book.(page 12). There is: Every Newtonian system, $$m_i \ddot{q_i}=\frac{\partial V}{\partial q_i}, \mbox{ } ...
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1answer
221 views

Why pendulum does not follow SHM for larger angular displacement?

Considering an ideal case(neglecting drag of air, damping etc.), a pendulum follows SHM if the angular displacement is small (upto 10 degrees). But, for large angular displacement(more than 10 ...
3
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1answer
71 views

How skydivers control their angular momentum?

As the title says, how do skydivers stop spinning from an out of control spin while in freefall? Doesn't conservation of angular momentum doom them to keep spinning, even if they make a small mistake ...
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3answers
462 views

Can the force acting on a body remain constant if the body is accelerating?

Since $F=ma$, the force should change if acceleration changes shouldn't it? And since acceleration is the rate of change of velocity, can velocity be constant if acceleration changes?
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1answer
52 views

Physics Problem: Falling Rocket [closed]

A rocket, of mass $M = 40kg$, falls vertically with a speed of $60 m/s = v_0$ and explodes in two fragments of the same mass when it's at $H=2km$ from the ground. Immediately after the explosion one ...
2
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1answer
193 views

Centrifugal force on a pendulum

Why don't we consider the centrifugal force acting on the bob of a pendulum while drawing the Free Body Diagram of a pendulum? It's also a sort of circular motion.
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0answers
13 views

Direction of acceleration in an oscillating pendulum [duplicate]

Consider an oscillating pendulum hung from a rigid wall. Neglect air friction and all. What's the direction of its resultant acceleration? Radial, tangential or somewhere in between? It should be ...
2
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3answers
135 views

Is centripetal acceleration mandatory for circular motion?

If we consider a case where a closed circular wall is present, and inside the boundary, just adjacent to the inner wall, two particles are placed touching the surface of inner boundary such that the ...
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3answers
90 views

Instantaneous cause [closed]

The position of an object has a rate of change called velocity. The velocity of an object has a rate of change called acceleration. Force applied is proportional to the acceleration of the body ...
3
votes
1answer
164 views

Why does this rotating cube move forward on impact?

I’ve been trying to mechanically model a cube tumbling down a straight slope and hit some difficulties early on. So as a starting point I want to look at the kinematics of a cube allowed to ...
79
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6answers
9k views

Does a gun exert enough gravity on the bullet it fired to stop it?

My question is set in the following situation: You have a completely empty universe without boundaries. In this universe is a single gun which holds one bullet. The gun fires the bullet and the ...
3
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2answers
65 views

Does decomposition of motion rely on Pythagorean theorem?

As an example, when analyzing a simple projectile motion with initial horizontal velocity in Newtonian mechanics, I'm enabled to decompose the projectile motion into the vertical and horizontal ...
0
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1answer
73 views

Momentum conservation in a small time interval

I recently solved a problem in which I used the "fact" that the momentum is conserved just before and just after a collision between two (or maybe more) objects but I am not sure whether this is true ...
0
votes
1answer
104 views

How does a ceiling fan blades redirect air throughout a room to cool you off?

I already know how a table fan works because of how the blades are angled. For a ceiling fan I am confused about how the blades cut through air to cool off things in a room?
0
votes
1answer
456 views

Centre of gravity vs centre of mass for a pyramid mounted on a cube, all sides of length $l$ [duplicate]

A uniform solid body is constructed using a square-based pyramid mounted on a cube. If each edge of the solid has length $l$ show that the centre of gravity of the body lies within the cube is, $\frac ...
1
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1answer
73 views

Potential Energy of Lagrangian system

I want to clear my basic understanding of Lagrangian system. I am confused about the potential energy for the Lagrangian system. According to this picture, m is suspended from a rigid massless ...
1
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1answer
74 views

Potential Energy Problem

We know that, the potential energy of a particle is $U= mgh$ where $h$ is the height from the zero potential point. But what I have found in Resnick's Fundamental of physics book is that they ...
0
votes
2answers
113 views

Conservation of momentum - finding the angle between broken parts

Let a stationary block explodes into 3 equal pieces .The speeds are also equal which is $v$. If I am asked to determine the angle between the broken pieces that are moving then how to deal with this ...
1
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2answers
350 views

Motion of center of mass

I was reading about COM and forces and came upon this in my book. If a projectle explodes in air in different paths,the path of the centre of mass remains unchanged.This is because during ...
0
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1answer
253 views

Energy dissipation due to frictional force in rotational motion

Let me have a ramp with length l and height h. What I want is to roll that ball on the plane without slipping . When I face this types of problem, I try to consider the rotational energy and kinetic ...
2
votes
3answers
165 views

Free falling body's deceleration

Ok, a body is falling with a velocity $70\sqrt{2}\ ms^{-1}$ and its final velocity must be 0 $ms^{-1}$ after falling a further 200 $m$. What is the acceleration required to bring it to a stop after ...
0
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2answers
71 views

Does it take less time to drop a ball than fire one horizontally (with $90^{\circ}$) [closed]

So I was arguing about this with my friend. If we take two balls and drop one from a certain height H and then fire another one with horizontally with some initial speed from the same height H, which ...
2
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0answers
67 views

Trouble with geometric proof of gravitational force inside a sphere

In Newton's superb theorem: An elementary geometric proof (Argument on Page 4, accompanying diagram on Page 11), the author attempts to prove Proposition 70 in Newton's Principia (gravitational force ...
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1answer
53 views

Looking at a falling person (vertically) from 60m to the surface, how much wind effect is going to be felt?

I am trying to work out horizontal ranges for a falling person from height (in 10m steps from 0m to 60m). I have used this site http://www.convertalot.com/ballistic_trajectory_calculator.html to ...
2
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4answers
624 views

Stone dropped from a moving train

This may look like a stupid question, but it is really getting to me. Imagine a train moving with an acceleration $a$, and a person drops a stone from the window. To an observer on the ground, the ...