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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How can make myself sure that I can apply Conservation of Momentum in a system?

How do I know I can apply Conservation of Momentum in the System ? And What happens if there is a Impulse in the system?
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3answers
249 views

Deceleration of a bullet [closed]

Taking into account gravity, air resistance, and wind velocity and direction. (And also temperature if it's actually relevant.) I know the muzzle velocity, the total distance the bullet traveled, its ...
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1answer
50 views

Definition of unit of force [closed]

As we know $1\ \mathrm{N}$ is the force which can accelerate $1\ \mathrm{kg}$ mass with $1\ \mathrm{m/s^2}$ acceleration. But for which surface is this definition given? I mean a $1\ \mathrm{kg}$ ...
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123 views

What has the potential energy: the spring or the body on the spring?

Particles have gravitational potential energy due to its position in the gravitational field. We say the particle has potential energy and not the Earth (the body doing the work). Why is it not the ...
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0answers
44 views

Given Newton's 3rd Law, how is a sea-pumped hydro jetpack possible? [duplicate]

EDIT: I dont think it's an obvious duplicate. That Q just asks how a water jet pack works. My Q asks how 2 forces in 2 opposite directions producing 2 opposite-equal reactions can somehow produce a ...
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2answers
197 views

How to calculate force / torque on non-flat lever, i.e. dolly

See attached image. The mass is being rotated on a lever where the pivot point (P) is a certain distance ($L_2$) from the right angle at the bottom. How do I calculate the force necessary to apply ...
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1answer
80 views

When to use a whole vector approach vs an energy approach?

My professor has just introduced two new ways to solve projectile motions. One approach involve using trigonometry and vectors and the other involves using the idea of conservation of energy. My ...
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1answer
73 views

State of academic fields of analytic mechanics and Multi Body Dynamics (MBD)

My question essentially contains two parts: one practical question and one philosophical question. Background I am an engineering student working in the field of Multi Body Dynamics (MBD). My ...
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1answer
191 views

What does the free body diagram for mass 1 look like?

In this situation: Enough tension is applied towards the right on $m_2$ so that $m_1$ starts sliding backwards. I am confused about what the free body diagram for $m_1$ looks like. Here is my ...
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2answers
463 views

Electromagnet Electricity Consumption?

Wikipedia states that - The only power consumed in a DC electromagnet is due to the resistance of the windings, and is dissipated as heat. Is this true? So powerful magnets like junkyard magnets ...
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2answers
85 views

Compression of spring when an object of given mass is placed on it

A question in my textbook says - A block of mass $m$ is released from rest onto an ideal non deformed spring from a negligible height. Neglecting air resistance, find compression $x$ of the spring. ...
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2answers
51 views

Can an Adequately Long Tube Float?

I was just pondering in my head one day (I don't recall what I was pondering), but I came across the thought: If an adequately long (and light) tube is placed in the atmosphere, can the difference in ...
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1answer
81 views

car suddenly stop on hill/ circular motion

For car a it's simple, kinetic friction= mass*9.8*1.0 kinetic friction =mass*9.8 a=kinetic friction/mass=9.8m/s^2 but for car 2 is what i would like to ask about: the centripetal acceleration is ...
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1answer
45 views

Maximum displacement of a projectile with $x$ initial velocity and drag resistance

So, as a personal project, I imagined a scenario where a projectile with an initial velocity $x$ is affected by air resistance (drag) but not gravity, and I wanted to find out the distance it would ...
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1answer
78 views

Will the Earth's rotation someday be synchronized with its revolution around the Sun?

When will the earth act like the moon with regard to one side of the moon always facing the earth. Will the earth one day get locked in a rotational orbit that has one side of the planet facing the ...
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1answer
194 views

How to calculate escape velocity and orbital velocity for a cubular planet?

Given a planet that is a cube, how would one calculate the escape velocity and the orbital velocity? For a circular planet with an even distribution of mass (aka center of mass=center of volume) the ...
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2answers
75 views

Why is it easier to drop on to a downslope?

On a bicycle, why is it easier to land from a drop or jump on a slope going downwards than landing on a flat surface or on an upslope? I've already heard answers such as "because that's how a bike ...
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1answer
141 views

What is the potential and kinetic energy of the international space station?

I know it's possible to calculate, but what formulas would I use to be as accurate as possible? I'd like to see how it works for something big and high like that.
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1answer
92 views

What is the outward force on the Moon that makes it go in orbit rather that falling straight to the Earth? [duplicate]

So, we know that the gravity is responsible for pulling the Moon towards the Earth. But because it moves in an orbit, it makes me think that there must be a force that is causing the moon to travel in ...
23
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2answers
4k views

If action equals reaction, how is it ever possible to win in martial arts?

In kick-boxing, when a fighter's leg hits an opponents leg, the outcome, based on Newton's 3rd law, should be the same for each fighter. It's not even important who kicked who, as in the moment of ...
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1answer
105 views

Understanding $F=ma$

I know the formula F=ma, but I truly need to understand its implications. Take this scenario for example, we have two bullets exactly the same weight and size (identical to each other). Lets assume ...
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1answer
468 views

Two objects at different heights, would they be traveling the same speed?

If I were to drop an object at a height of 15 feet, then another object of the same mass at 20 feet, would both objects be traveling at the same speed? What would be the speed of which they are ...
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2answers
162 views

Apply force to one end of a rod in space: why not purely translational? [duplicate]

Why does applying force to a rod in space (or any other isolated systems) on one end leads to both translational and rotational motion? Here's my logic: suppose there is a rod in space. We ...
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1answer
153 views

Action and Reaction between two people

When you hit a person, you apply a force on him. Then according to Newton's third law, there should be an equal and opposite reaction, and that should act on you. So, why don't you fall backward? Is ...
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3answers
76 views

Finding velocity from distance and gravity

Basically, I have a problem that asks: An object is launched to a height of 2 miles, what was it's initial speed and time. Now normally something like this would be fairly basic. The problem ...
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1answer
92 views

Would a titanium suit save your life from a piano falling on you? [closed]

Or would the piano dent the titanium and kill you?
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28 views

How to write the moment equation about a rotating as well as translating point?

I want to write the moment equation in Ground frame as well as the frame of reference of the point (which I think should be a rotating frame of reference) for the following situation. $C$ is the ...
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2answers
49 views

Find $\oint xdx+2ydy+3zdz$ on the line segment formed by points $A(1,0,-1)$,$B(2,5,-1)$ [closed]

Find $\oint xdx+2ydy+3zdz$ on the line segment formed by points $A(1,0,-1)$,$B(2,5,-1)$ My approach: First I find the line segment formed by $A,B$ which is $\vec ...
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3answers
334 views

Are Newton's laws followed in non-inertial frame of references having all their objects and observer moving with same acceleration?

Consider a hypothetical scenario. In our universe there are two merry-go-rounds 1 and 2 and a distant planet. There is no other object having mass. There is a robot X on the planet. There are two ...
2
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3answers
465 views

Variation of Kinetic Energy

Question: Which of the following graphs correctly describes the variation of kinetic energy with time of a block when it slides down a smooth inclined plane from rest? The answer is C but I do not ...
2
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0answers
96 views

Why do Lagrange multipliers work in mechanics?

I understand that it is not always simple to find generalized coordinates that satisfy the constraint equations, so we try to find an alternative (more mechanical) method that yields curves that ...
2
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2answers
53 views

Does $v^2=v_0^2-2gh$ work if the positive axis is up and the initial velocity is down?

In the situation where the positive axis is up, the acceleration due to gravity is $g$, and the velocity is represented by the equation $v^2=v_0^2 - 2gh$. This works great if the initial velocity is ...
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1answer
85 views

Circular motion with friction (time dependent velocity)

I am trying to understand how circular motion problems can be solved when we introduce friction as a variable in them. As i understand this problem, the centripetal force, which points towards the ...
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0answers
86 views

Are new discoveries in quantum physics (e.g. Amplituhedron) supporting one of the classical QM interpretations? [closed]

Are new discoveries in quantum physics (e.g. Amplituhedron, Higgs boson) supporting one of the classical QM interpretations? For example Copenhagen, Everett many worlds or Penrose interpretations. Or ...
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2answers
772 views

In wave motion of a string both kinetic energy and potential energy are minimum at $y=y_\text{max}$ then why does the string comes down again?

In wave motion of a string both kinetic energy and potential energy are minimum at $y=y_\text{max}$ then why does the string comes down again? As everything in tries to attain lowest energy possible ...
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1answer
87 views

Will dynamo generate electricity with reverse spin?

Will a dynamo generate electricity when it is spinning in opposite direction? If we alternate the rotation direction every minute, will it still generate electricity? How?
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0answers
31 views

Is it possible that any spatial variation in press disturbance without gravity?

When gravity (and buoyancy), acting as the only body force of a liquid, is ignored. Is it possible that any spatial variations in pressure perturbation are the result of fluid motion or some other ...
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1answer
81 views

How to set up equations of forces for 3 springs connected to each other in an elevator?

In the above diagram the elevator is moving downward with acceleration $a_E$ and velocity $v_E$. All 3 masses are given as $m1,m2,m3$. The question is how much has the middle spring stretched from ...
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0answers
42 views

Collision and resulting compression

During collision is there any compression of the surface? if yes, the collision is considered as elastic or non elastic ? Does the compression produce the impulse force or its due to the impulse ...
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0answers
25 views

Size of meteor-made crater [duplicate]

I am reading "What if" piece https://what-if.xkcd.com/20/ and I am very interested in how can one ever estimate the size of a crater? How can you ever know, it must depend on energy of a falling body ...
4
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1answer
199 views

Why is the apparent weight smaller when you crouch down on a scale?

I am having a problem understanding the concept of the apparent weight change when you crouch down, stand up, and jump on the scale. What is happening that makes the scale change?
1
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1answer
303 views

2D Mass Spring System - Where does $m_3$ go to?

I am struggling to frame proper equations for the following two-dimensional mass spring System: 1D Model Basics first: I started with a simple one-dimensional mass-spring System to model something ...
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0answers
414 views

How do you calculate the output force of a machine?

Based on a force inputed in a machine, how do you calculate the force outputed? I would have thought you could do this with a simple torque balance but this does not always appear to be the case. For ...
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2answers
51 views

Bending + Contact Force

When we have 2 bodies in contact with each other, for example a book lying on the surface of a table. The table's molecules bend a little bit because of the weight of the book thus producing the ...
0
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1answer
83 views

Determining the instantaneous axis of rotation [closed]

Given the following image The question states ,a heavy disc with radius R is rolling down hanging on two non-stretched strings wound around the disc very tightly.THe free ends of the strings are ...
0
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1answer
61 views

How much power is needed to drive two times faster?

Suppose a cyclist riding at speed $v$ decides to accelerate to speed $2v$. Does she have to generate $8$ times more power to sustain that speed? $P_1=F_dv$ If we double the speed, (it usually ...
2
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2answers
848 views

Work done by a non-conservative force and change in potential energy

I know that the work done by a non-conservative force is equal to the change in total mechanical energy (from Work-Energy Theorem). But I read in a place that "Non-conservative forces don't affect ...
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1answer
31 views

Can you explain the dynamic of forces working in the video?

Lifting Against Gravity - Breaking Magic - Discovery Channel In this video, a woman uses Physics, so that it is difficult to lift her off the ground. The explanation that the video gives at the end ...
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2answers
126 views

Is friction a function of surface area? What is the microscopic workings of friction?

I know the friction is given by the following equation $$\mu F_N=F_f$$ which tells me friction is independent of surface area, but how do I characterize it as such if I want to add surface area into ...