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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Center of mass two particles with one moving

Two small particles of mass $m_1$ and mass $m_2$ attract each other with a force that varies with the inverse cube of their separation. At time $t_0$ , $m_1$ has velocity v directed towards $m_2$ , ...
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A ball rolling in a bowl [on hold]

There is a small ball with a radius of 2 mm inside of a bowl with a radius of 22 mm. If the bowl is tilted 1 degree in any direction, what does the slope of the bowl need to be in order to get the ...
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31 views

Length of the missing part [on hold]

I have got a very interesting question. A car is driving this way on the picture down. In the looping is a missing part. The radius of the looping is r = 40cm. The car starts at the height h = 3r. If ...
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4answers
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A force opposing Gravity

Every Action Has An Equal and Opposite Reaction (Newton's Third Law.) If this is the case, does gravity have an equal-opposing force? From asking around I still haven't got a very clear answer; ...
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3answers
56 views

Foucault pendulum initial velocity

This is a basic question I can't solve and it seems it is not addressed on the web. Sorry for my lame painting skills. Assume we have a foucault pendulum suspended in the north pole. the pivot is ...
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2answers
52 views

Inertial frames

I'm just starting my study of relativity, and I have a rough understanding of the connection between inertial frames, newton's laws, and galilean transformations, but I'd probably benefit more if ...
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1answer
36 views

At the instant of release of an object from rest. Is the only force that can act its weight?

Q3 from a mechanics exam past paper: I can do parts i) and ii) but for iii) in finding the angular acceleration, i used $C=I\alpha$, where $C$ is the applied couple or torque, $I$ is the moment of ...
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4answers
102 views

What do you exactly mean when you say that momentum is conserved?

I am taking for granted that when we say that something is conserved it is understood 'in its full integrity'. Energy is represented by a number (of J, or other) and is usually conserved. But ...
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calculate gravitational force [on hold]

an object weighs 977N on the surface of the earth and 244.25N if the earth is remoulted. The radius of earth is 6.4×10$^4$m and its mass is 6×10$^{24}$kg. Calculate the radius of remoulted earth and ...
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1answer
40 views

Relationship of multiple particles under collision [on hold]

Consider 3 particles. All 3 particles travel along the x-axis. The 1st particle possesses some mass, m, and its initial position is somewhere on the negative x-axis. It has some (positive) velocity ...
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1answer
31 views

Amplitude of motion for a cart on an inclined plane attached to a spring

A very practical question. So, let's imagine that we have a small cart attached to a spring lying on an inclined plane. If I move my cart by 10 cm (measured as if there were a ruler lying along the ...
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0answers
36 views

How to find tension in the cantilever brakes?

In the left side example of cantilever brakes, how do I find the tension in strings DE and DC, in terms of T. According to me applying force balance equations, horizontal and vertical forces should ...
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7answers
2k views

Why do we fall down when the bicycle slows down? [duplicate]

My question is: It is easy to balance a bicycle when it is moving at a fairly high velocity, say 7 m/s or 25 km/hr. But when a bicycle slows down, it is hard to keep it upright, and the person riding ...
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1answer
57 views

Conservation of linear momentum, when is it conserved?

Will Linear momentum be conserved in a non-inertial frame of reference? In other words what is the fundamental condition for linear momentum to be conserved? Also which is more fundamental- Newton's ...
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1answer
29 views

Electrical Analog of a Chain of Springs

I'm trying to wrap my head around the Force $\rightarrow$ Voltage analogy between mechanical and electrical systems. I have a mechanical system where masses are connected by springs in series, and ...
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2answers
64 views

Force Diagram for K&K 2.13 [on hold]

I have been (independently) working on Problem 2.13 in Kleppner and Kolenkow's An Introduction to Mechanics and come to an answer which conflicts with the hint the authors provided in the book. The ...
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2answers
109 views

How can Excel be used to model the flight of a rocket? [on hold]

Firstly, sorry for any silly mistakes or improper use of this website - this is my first time using it! I am trying to use Excel to model the flight of the Apollo 11 Saturn V rocket using the real ...
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1answer
52 views

Will this achieve linear movement of a closed container?

Can I create a device that moves in one direction with a design like Figure 1? I suspect that the forces cancel each other by the recirculation. It is a simple exercise of action and reaction, but I ...
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2answers
73 views

What is the “associated scalar equation” of equations of motion?

In an essay I am reading on celestial mechanics the equations of motion for a 2 body problem is given as: $$\mathbf{r}''=\nabla(\frac{\mu}{r})=-\frac{\mu \mathbf{r}}{r^3}$$ Fine. Then it says the ...
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1answer
33 views

What does an $n$-body system with constant $T$ and $U$ look like?

Can someone give an example of a system where the kinetic $T$ and potential $U$ energy are constant (but not zero)? Here's what I have in mind: Say you have $n-1$ satellites of negligible mass ...
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5answers
214 views

Forces as vectors in Newtonian mechanics

I seem to be confused about the nature of forces as vectors, in the basic Newtonian mechanics framework. I know what a vector is as a mathematical object, an element of $R^3$. I understand that if a ...
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2answers
106 views

Power to suspend a mass in air

How much power is needed to suspend a mass in the air? The four parts below deal with the same problem. I post them all here, should there be some subtle things I didn't see. The textbook problem A ...
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1answer
329 views

Centrifugal force affecting satellite

I'm trying to explain the behaviour of a geostationary satellite using different frames of reference. Inertial frame: The satellite has a circular motion with angular velocity $\omega$. The ...
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4answers
70 views

Find a central force given the orbit

I've been trying to solve the following problem for a long time. Let's consider a particle of mass $m$ in $\mathbb{R}^3$ with polar coordinates $(r,\theta,\phi)$. The particle moves on the orbit ...
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1answer
54 views

Centre of mass, integral

I was answering a question on proving the parallel axis thereom for angular momentum and came across this: $$\int Yy'dm=Y\int y' dm=0$$ Where the position of the center of mass of an object is given ...
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2answers
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Does the bolt really rise upward?

In this site,when the elevator rises up,the bolt falls downward under the force of gravity . But when distance is measured it is shown that it rises up,velocity becomes 0 & then it falls with ...
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3answers
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What is the intuition behind $gt^2/2$ equalling the distance something falls after $t$ seconds?

Let's say $g=10\ \text{m/s}^2$ and it drops for $3$ seconds. For the first second it will drop $10\ \text{m}$, the second it will drop $20\ \text{m}$ ($10 + 10$) and the third second it will drop $30\ ...
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Finding the work Done by Normal force? [closed]

The problem is as follows: There is a Right Angled Wedge fixed in an box against left wall. The angle of incline of the wedge is 45 degrees from the horizontal. The height of the wedge is same as ...
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3answers
54 views

Confusion relating the application of Work-Energy theorem

Could someone kindly explain the solution to my confusion? When we walk at a constant speed up a steep hill, is work being done? Then why isn't our kinetic energy changing as work done is equal to ...
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1answer
38 views

Pushing a crate on a friction floor [closed]

A man is pushing a crate at a constant velocity. there is a friction between the floor and the crate of $$\mu =0.41.$$ The pushing force is directed downward at an angle $\theta $ below the ...
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1answer
40 views

Displacement of an object due to opposite and equal forces acting at different times?

This question is about mechanical waves in solids, the speed at which forces propagate through solids, and the displacement that might occur due to unequal starting times of equally sized forces. ...
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1answer
36 views

Action Reaction Pairs and Work

Say that a ball is sitting in front of a compressed spring launcher. The spring is then released. The spring applies a force on the ball for a certain distance. This force is accompanied by an equal ...
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1answer
40 views

Work done by Internal Forces

Why is it that internal forces do not change the potential energy of the system? Assume that a man stands on earth with a dumbell. If the dumbell is the system, when it is raised a height h, the work ...
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102 views

Integral ambiguity

I'm a bit confused with some notation I encounter in physics calculus. Consider this: Taken from here. Integration operates on functions, correct? What does it mean to integrate $\frac{d{\bf ...
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1answer
57 views

Massive ropes and tension

Consider the diagram bellow, a massive string hanging in equilibrium My question is this: Can we take any 2 random point on the rope, say A and B and then use $\sum F=0$ on the rope between them: ...
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1answer
23 views

What is the work done below proportional to? [closed]

A raindrop falls from a certain height to the ground, with a terminal velocity u. The viscous force is F = 6*3.14*n*r*v, where n is the coefficient of viscosity, r is the radius of the raindrop, and v ...
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0answers
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Similarity in two events from Dynamics point of view [closed]

What is similar from dynamic point of view between book lying stationary on horizontal table and rain drop falling down with constant speed? I can find two similarities Force acting on them is ...
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1answer
139 views

Why are D'Alembert's Principle and the Principle of Least Action Related?

Why do we get the same differential equations from both principles? Surely there is a fundamental connection between them? When written out, the two seem to have nothing in common. $$\sum _i ( ...
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2answers
31 views

Is centrifugal force equal in magnitude to the centripetal force in the frame of a body undergoing circular motion?

I was working out the minimum tangential velocity required for a swing to complete a full revolution and assumed the centripetal force is equal to the centrifugal force, so that I could set the weight ...
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2answers
32 views

Finding coefficient of friction between block and plane [closed]

An inclined plane makes angle $\theta$ with horizontal. Upper half plane is perfectly smooth where as lower half is rough. The block of mass m starts sliding from top. If the block again comes to rest ...
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0answers
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What is the angle of projection when at maximum height the speed of a projectile is half the speed at half the maximum height? [closed]

I have been struggling with this problem: The speed of a projectile when it reaches its maximum height is one half of its speed when it is at half its maximum height. What is the initial ...
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1answer
28 views

Modeling a stool with three legs pushed on one leg

If a stool with three legs is pushed (horizontally) on one leg in the direction of the axis passing through the other two legs, it starts both moving and rotating. Is it correct to assume 1/3 of ...
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1answer
59 views

Hooke's Law: why is only one force considered?

I have a question about Hooke's Law springs. What I learned is that a Hooke's Law spring gives a force F pushing left and right and each force equals $k \cdot |l-l_o|$ Let's say there is a mass ...
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7answers
391 views

Hit by two cars with same momentum but different mass. Which is more painful?

Suppose they have the same contact area with you. The term "painful" is a bit ambiguous. Let me ask in another way: Two cars with same momentum but different masses are going to hit a wall. You ...
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1answer
47 views

Reduced mass and harmonic mean

In two-body problems, a reduced mass has the form: $\frac{m_1 m_2}{m_1+m_2}$, which by appearance, is half of the harmonic mean of $m_1$ and $m_2$: ...
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1answer
59 views

Why is the range for a particle thrown at 90 degree same as that of a particle thrown at 0 degree?

There is a derivation given in my book which concludes to the fact that the range is same for two angles of projection, provided they are complementary. I fail to understand this fact. For example, ...
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1answer
44 views

Will A Vertical Projectile Travel the Same Distance as A Horizontal Projectile

If a projectile is fired vertically from an initial height, $h$, above ground level, and an identical projectile is fired with equal initial velocity from the same initial height in the horizontal ...
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1answer
66 views

Finding equilibrium of mechanical system

A system is described as follows: Consider a system consisting of two rotating bars of length $l$ and with uniform mass density and each with total mass $m$. The bars are attached to a common ...
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2answers
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Put a bullet into orbit around the moon

While I was watching this beautiful video, the absence of air friction pushed me to ask myself: While standing on the surface of the moon, what is the initial velocity by which you can fire a bullet ...
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1answer
65 views

How can I actually push heavier objects?

I've been thinking about Newton's third law lately because I couldn't understand a few things and I think I actually answered my own question. Could someone confirm if my reasoning is right or show me ...