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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The velocity of the flowing coming out of the balloons?

Last day , when i was working on two interconnected balloons , a question was kicking my brains !!! This is the explanation of the question: First , suppose a system that composed of two spherical ...
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100 views

Motion of a wheel with an added mass to its edge [closed]

Imagine a wheel with homogeneous mass distribution, but there is a mass concentrated to its edge at a specific point. The wheel is rotating over a horizontal surface with a given initial velocity. How ...
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50 views

Why does the pressure sensor give the same value of pressure no matter how it is oriented?

Let a small pressure-sensing device be suspended inside a fluid-filled vessel. ... We find by experiment that at a given point in a fluid at rest, the pressure has the same value no matter how the ...
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273 views

Parallel axis theorem

For this question we are working in 2-D space. Let's say that we have an arbitrary body. I know the inertia with respect to a perpendicular axis (to the body, that is) that passes through a point (A). ...
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143 views

Understanding variable mass equation for mass ablation/ejection

The "Variable-mass system" entry in Wikipedia, under the "Mass ablation/ejection" title, shows: $$p_2 = (m+dm)(v+dv) + u(-dm)$$ The parameter $p_2$ is for the momentum at $t+dt$, meaning $p_2 = ...
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443 views

What forces cause the centripetal acceleration in circular motion on a merry-go-round?

Suppose you stand on a merry-go-round spinning at $f$ revolutions per second and you are $R$ meters from the center. What forces act on you? If you were tied to a rope like in Fig 2 you would follow ...
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72 views

Will terminal velocity exist on this imaginary planet?

If the atmosphere of an imaginary planet is really thin like 100 particles per cubic centimeter (density of the closest resemblance of vacuum made on Earth) and has mass say, 15 times than that of ...
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116 views

Force on a solid cylinder that is rolling on an accelerating block

Given: $m,R,I=mR^2/2, F,M$ and no traction between $B_2$ and the ground find $a_1, a_2$ (the accelerations of the CMs of $B_1$ and $B_2$ respectively).$B_1$ rolls on $B_2$ without sliding due to ...
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206 views

Flipping a bottle

I tried to do this experiment recently at school and my house. I started the experiment by having three same type of bottles with the labels A,B and C. Bottle A has been fully filled with water, ...
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2k views

Impulse and force in a karate chop, can we maximize force minimizing the time of impact?

I have heard that we can maximize the force by minimizing the time of impact in a punch. If that is true, the paradox is if we increase the time of contact with the same amount of force still we ...
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178 views

What really is “inertial force”?

In Fluid Mechanics we often see the term inertial force when discussing Reynolds number. The problem is, I didn't really get what's this inertial force. Basically, the notion of inertia I have is that ...
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536 views

Where do Newton's Laws not work? [closed]

I'm working on high school level project about Newton's Laws and I picked topic that describes situations, where they dont work. Can you name any practical cases where they do not work? Why do they ...
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76 views

Why is it that friction apparently decreases with speed? [duplicate]

Whilst thinking of a trick where a magician pulls a tablecloth directly from under a full set dinner (a classic) I wondered why friction doesn't increase as speed does. I get that they use a pretty ...
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110 views

Problem in understanding Newtonian 2nd law

In Resnick, Halliday, Walker s' Principle of Physics , I found this question : Two forces are acting on a block on a frictionless floor. On the left of the block $3~\text{N}$ & on the right of ...
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1answer
104 views

Confused about gravitational potential energy [duplicate]

So learning the concept of gravitational potential energy, my professor says that when lifting an object without any acceleration, the force we exert on the object to lift it is the same as the force ...
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255 views

Effect of movements of astronauts on International Space Station

I know that astronauts move in and around in ISS. When they move they also touch the modules of ISS and sometimes they apply force on the module to move. When this happens, as far as I know it affects ...
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299 views

Why did I get this dynamics question wrong? [closed]

I'm wondering as to why I got this physics question wrong, despite it being quite simple in nature. I believe that I missed something while working on the problem. Basically, the question involves ...
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2answers
870 views

Why does a Ball bounce back if Forces are Equal and Opposite?

When a ball is thrown onto a wall, the ball exerts a force onto the wall. According to Newton's Third Law, the wall will exert an equal and opposite force to the ball. Thus, how would the ball be able ...
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78 views

Centrifuge speed of an object higher than a stationary orbit

In the question At what altitude above equator do gravitational and centrifugal forces cancel each other?, I asked how high a tower on the equator has to be such that at its top, gravitational and ...
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37 views

Possiblity of predicting behavior of system when properties described as functions over space?

Suppose I am given a system that consists of a distribution of charged particles(which are all over space and are point-charges). They are described by a set of functions instead of variables. These ...
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264 views

Possible Deflection Distance For Falling Object

I work for a company selling tethers that prevent tools on building sites from falling away from the user. One of the problems that has come up is that objects can deflect horizontally when they ...
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444 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 ...
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80 views

How does acceleration affect the orbit?

I want to know what roughly happens if we hit an orbiting body a little. And how is it possible that most of the objects have seemingly circular orbits around. How do they stabilize? I ask because it ...
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173 views

Why does Newton's Third Law not preclude any motion at all? [duplicate]

When walking, if I apply a force of 2N on the earth, the earth applies a force of 2N back on my feet due to Newtons 3rd Law of Motion. These 2 forces are equal in magnitude but opposite in direction, ...
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190 views

Basic buoyancy question

If I have a cup of water filled with air at the bottom of a pool, then when the cup is "upside down" the air doesn't leave because the water pressure is pushing it up against the top of the container. ...
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144 views

Why is $dr/dt= -V$

In the solution, it says we have $dr/dt= -V$ (polar coordinates) How? I can't see how this can be possible, we know that $r(t)=V/\omega(t)$, and that's it.
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243 views

How to identify whether the friction is kinetic or static?

The body 'A' is moving forward with certain acceleration over the ground. The ground applies a kinetic friction force on 'A' in backward direction to oppose the relative motion. The block 'A' also ...
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220 views

What are some good resources for learning how to apply vectors in physics?

Although I don't have any problems with vectors when using them in Mathematics but I am having a hard time using them in physics. It is really frustrating me. Can you please recommend me some good ...
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556 views

Calculating the rate at which a car turns

This is going to be difficult to describe, as I have no real concept of this sort of physics, so please bear with me. If this is too much or beyond the scope of this website, I apologize. I am making ...
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149 views

What is the inertia caused by angular momentum when twisted on it's rotating axis?

I would like to provide a more thorough answer to this question here http://aviation.stackexchange.com/q/3709 but I realized I don't know enough about angular momentum. If an airplane wheel is ...
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939 views

Force exerted on ceiling by a simple mecahnical system

I have a simple static mechanical system, but I reach a conclusion that seems to me counter-intuitive: There is a pulley fixed to the ceiling and there is a weight fixed to a rope which goes ...
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1k views

How much force is required to compress air?

How much force (Newtons) is required to compress normal air in a chamber to 2 atm? For example, if I had a sealed piston pump, how much force would need to be exerted in order for the air to be ...
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326 views

Motorbike with parachute vs normal skydive

Had a strange discussion in the coffeeroom today. The background was a story about a guy that took his motorcycle to transport himself to the airstrip to do a skydive. Since there is no place to put ...
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2k views

Why is force dependent on acceleration, not velocity?

According to $F = ma$, force is a result of acceleration and mass, right? However, I don't understand why velocity is not used instead of acceleration. A train moving at 100 miles/hour will still ...
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822 views

3D ballistic trajectory with quadratic drag. Calculating position and velocity at time $t$

A particle starts at the origin and has an initial velocity represented by a 3D vector. The particle experiences gravity and air resistance with quadratic drag (based on velocity^2). What I've been ...
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3k views

Confusion over the gravitational potential energy inside a sphere

I'm confused over the concept of gravitational potential energy inside a sphere. I understand that the gravitational potential energy inside the sphere is supposed to be a constant $U = ...
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108 views

Homework Question involving Momentum [closed]

I'm trying to solve a homework problem as review for an exam I have tomorrow and I was wondering if someone could help explain it to me. It is as follows: You are at Lowe’s shopping for bricks ...
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235 views

Energy of a damped oscillator

$$ E=\frac{1}{2}m\left(\frac{dx}{dt}\right)^2+\frac{1}{2}m\omega_0^2x^2. $$ This is the equation for the energy of a oscillator. The second term is the potential energy. Now, my question is, will ...
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1answer
3k views

Confused about relating spring force to maximum distance

I keep working through this problem and getting the wrong answer: A spring with spring constant k is positioned vertically and then compressed from its equilibrium length by a distance Δy. A ...
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2answers
145 views

Acceleration at two points on a rigid body

The rod AB is falling while sliding on the friction-less wall and the floor. I need to find the acceleration of the points A and B. I am sure that the point A is freely falling, so its acceleration ...
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732 views

Toppling of a cylinder on a block

A uniform cylinder rests on a cart.The height and diameter is given.coefficient of static friction is given.How can i find the minimum acceleration of block such that the block topples? Morever what ...
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1k views

Where does this derivation of the equation of motion for a simple pendulum go wrong?

I am attempting to derive the following equation of motion for a simple pendulum: $$\theta''(t) = - \frac{g}{l} \sin(\theta).$$ For background, see this Wikipedia article. I understand this page ...
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2answers
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Finding the optimal angle of a projectile motion [closed]

I am trying to solve a task in which I need to calculate the optimal angle($\alpha$) with which the projectile will land the furthest from a height ($h$), so what I basically have is the equations for ...
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802 views

Pressure difference between 2 points in an accelerated fluid

Consider a liquid in a tub and this tub is accelerated. And so the liquid will have a slanted surface. I am clear about finding pressure difference between two points in the fluid having same height ...
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651 views

How can spatially extended objects behave like point particles?

Wikipedia states: Sometimes due to specific combinations of properties extended objects behave as point-like even in their immediate vicinity. For example, spherical objects interacting in ...
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1k views

Fluid Mechanics Piston Problem

The actual problem: A hydraulic car lift has a reservoir of fluid connected to two cylindrical fluid filled pipes. The pipe directly below the car has a diameter of 1.8 m. the pipe on which the ...
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3answers
1k views

Effect of incoming force on linear vs. angular velocity

First of all, I should note that I'm a programmer and have only an extremely basic understanding of physics; I only know how to explain my question in layman's terms and I apologize if I'm unclear or ...
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209 views

The circumference of the Moon's orbit around the sun?

I know that it orbits the sun in what looks like a 12 sided polygon with rounded corners. But I can't seem to find the radius/circumference anywhere.
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606 views

Newton's 3rd law [closed]

So i read this in some article on the net Consider a boy is standing at distance of 10 metres from the wall. Boy holds a rubber ball and cloth ball in his hands. Firstly, the boy throws rubber ...
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707 views

Does anti-lock braking system (ABS) perform reverse rotation sometimes?

In cartoons we can see, how vehicles brake by rotating wheels reverse. Will this be helpful sometimes in real situations? I know that the main tactics of ABS is to maintain tractive contact. But may ...