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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Why are these periods the same: a low earth orbit and oscillations through the center of the earth?

Related: Why does earth have a minimum orbital period? I was learning about GPS satellite orbits and came across that Low Earth Orbits (LEO) have a period of about 88 minutes at an altitude of 160 ...
0
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0answers
23 views

How is work done by a system in static equilibrium? [duplicate]

For a little colour: this came from my wondering why fork-lifts are hydraulically driven, rather than electromechanically. My question is this: why is it that some systems, while in static ...
0
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1answer
77 views

Apparent weight on a hill and in a ditch [closed]

first time posting. I'm trying to solve these 2 problems. I have a solutions I just don't know if I'm right...seems odd that they are the same answer... 1) If you are driving over a hill of ...
2
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0answers
147 views

How to calculate launch angle for tangentially launched satellites?

What is the value of theta for a satellite not falling back to the Earth if it is launched from the direction tangent to the surface of the Earth? I have found the escape velocity which is 11.18km/s, ...
0
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0answers
55 views

How can we describe the trajectory of an object projected into a viscous fluid?

Can we quantitatively describe the motion of a particle inside a fluid? Let us consider the case when an object (say a sphere, so that stoke's law holds true) is projected into a fluid of viscosity ...
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4answers
122 views

Is it possible to prove that projectiles with drag will not travel in a parabola under the theory of classical mechanics?

Can you prove that projectiles will travel in a parabola, provided the acceleration due to gravity $g$ does not vary significantly along the trajectory? This should take air resistance into account. I ...
1
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1answer
57 views

How to calculate required energy to displace a pendulum?

How can one calculate the amount of energy needed to displace pendulum with given mass m and string length L to $\alpha$ degrees from resting position when acceleration due to gravity is known?
3
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2answers
244 views

What is the mathematical definition of work?

I'm looking for the pure mathematical definition of work, but I haven't yet learned line integrals. My book says that the work due to a force ${\bf F}$ from point $A$ to point $B$ is $$ W= |AB|\cdot ...
6
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2answers
298 views

When falling through the air, does swinging arms/legs actually help anything?

Let's say someone jumps off an Olympic-sized diving board into a pool below (so air resistance is negligible). As soon as they jump, they start swinging their arms. Does this help them stay upright ...
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1answer
48 views

If a planetoid was wet and you spun it would the water move to the equator?

If the moon was alone in space and covered in X feet of water and it began to rotate would it displace to a bias along the equator?
0
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1answer
817 views

Calculate the weight that a hot air balloon can carry [closed]

Given a hot air balloon of radius 10 meters and negligible mass, calculate the maximum weight it can carry if the density of outside air is 1.2 $\frac{kg}{m^3}$ and the density of inside air is 0.9 ...
3
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2answers
487 views

Potential energy of a rotating bar

I have a bar of length $L$, mass $m$, and negligible width. The bar can rotate along an axis through its center of mass (the rotation is in the $x$-$y$ plane), and also can move up and down (in the ...
3
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2answers
141 views

Physical Role of Batter in Baseball

Physically, what is the role of a batter in baseball? My question is inspired by How does the speed of an incoming pitch affect the speed of a baseball after it's hit? The answer to that question, ...
1
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0answers
18 views

Is acceleration quadratic or linear outside of a gravity field? [duplicate]

So as I understand it: If you hit a wall at twice the speed you hit four times as hard? I often ask people this and everyone says "at twice the speed you hit twice as hard". $K=\frac{1}{2}mv^2$ is ...
3
votes
2answers
894 views

Period of pendulum in falling lift

A simple pendulum suspended from the ceiling of a stationary lift has period $T_0$. When the lift descends at steady speed, the period is $T_1$. When the lift descends with constant downward ...
6
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1answer
360 views

How does my kitchen scale know I'm holding it?

If I switch on my electronic kitchen scale while it's on the table, it reads 0 grams. If I pick it up, it reads around -500 grams. Conversely if I switch it on in my hand it tares to 0g and then reads ...
1
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1answer
74 views

What force does a tall building exert on air?

I once heard that a tall building, let's say 10 stories, actually causes wind to blow by virtue of simply existing. It also was said that is why metropolitan downtown areas tend to be windy. What are ...
1
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2answers
398 views

Kinematics question - Newton's Law of Motion [closed]

Question: Find the mass M of the hanging block in the following figure which will prevent the smaller block from slipping over the triangular block. All the surfaces are frictionless and the strings ...
0
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1answer
56 views

Kinematics - moving body [duplicate]

If I have an inclined plane, which has acceleration $\alpha$, will a block placed on the inclined plane slip back with the same acceleration? (considering that the surface is frictionless)
0
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1answer
103 views

How to discover the $F = m\cdot a$ equation from scratch? [duplicate]

Is there a paper or a book that conceptually 'discover' the Newton's famous formula? I've been thinking about this equation, and I really don't know it for sure. Did Newton empirically noticed that ...
1
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1answer
121 views

Work done in pulling a rope from a boat

A boy sitting on a boat pulls on a rope with a constant force $F$ over a duration of time $t$. The other end of the rope is either tied to a bridge or to another freely floating boat of equal mass. ...
1
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1answer
45 views

Effects of firing shells on the Earth's angular momentum

During a certain war, millions of shells were fired by country A towards the west, and even more shells were fired back by country B towards the east. The average momentum of each bullet were the same ...
2
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1answer
60 views

Converting Point Gradients to Rotational Representation

I'm a PhD student in an unrelated field. It's been a very long time since I've done physics, and I've run into a problem in my research which I think is actually a physics problem. Basically, I have ...
0
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1answer
312 views

Leg Press & Actual Lifted Weight [duplicate]

I was doing leg press at the gym today and was curious how much weight I actually lift when I do the exercise as compared to when I do a squat. Suppose I load $w_L$ onto the machine, which has an ...
2
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2answers
78 views

Having trouble understanding how the centrifugal force works

I thought that I understood the centrifugal force earlier, but I can't seem to grasp how it interacts when considering that everything is relative? Let's imagine that you are the only one in the ...
0
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1answer
93 views

What is the laplace transform of a single mass?

I'm trying to get a transfer function of F=ma in the Laplace domain. This should be simple, but yet I'm confused. The transfer function is displacement over force. ...
0
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1answer
93 views

Finding the minimum radius of the pivoted disc

Here is a question based on Simple Harmonic Motion that I tackled just now. However I think I am having an approach to tackle this but I am not sure about it. Ouestion: A uniform disc of radius ...
0
votes
1answer
140 views

Moving a bar magnet towards a freely hanging coil

"A bar magnet is moved towards a freely hanging coil. Determine if the coil stays stationary or not. If it moves, determine if it moves away or towards the magnet." My hypothesis: From Lenz's law an ...
0
votes
1answer
276 views

Asymmetry of induced e.m.f due to a bar magnet falling through a coil

It is well known that as a bar magnet falls freely through a coil, an electromotive force is induced in the coil by Lenz's Law. However, it appears that the peak e.m.f induced (ignoring the ...
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4answers
121 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. ...
0
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1answer
91 views

Figuring out the time period of an Atwood system

SO I was working on Atwoods, when I came up with the following problem, It is more complicated but i should understand this simpler scenario first. As shown in the diagram above, (Atwood machine), ...
12
votes
5answers
738 views

Compressibility and the form of Newton's second law in fluid mechanics

In deriving Euler's equations for fluid mechanics, in particular $$f=\rho \partial_t v +\rho v\cdot \nabla v$$ for some body force $f$ (e.g Landau & Lifschitz 2.3) one assumes the continuity ...
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2answers
229 views

How to know the Direction of the Acceleration Vector?

If the exercise doesn't give you the direction, how to know the correct one? Sometimes I assume its to the right and it was actually to the left, and I get everything wrong. Example here: How can I ...
1
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1answer
175 views

What factors indicates inelastic collision?

I am watching this example from Wikipedia: I am wondering what factors would indicate that the collision of 2 objects will be inelastic (I know macroscopic scale impacts are never perfectly ...
1
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2answers
511 views

Help explain how direction change relates to acceleration [duplicate]

I was doing some simple harmonic motion problems and I came across this picture describing the position, velocity and acceleration of a linear oscillator. At the moment in time when v is 0 the ...
1
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0answers
147 views

Question about Atwood Machine and Changing Masses

Say we have an object of X Newtons on the ground called object 1, and it is connected to another object called object 2. If we change the mass of object 2 in intervals until object 1 < object 2, ...
0
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1answer
211 views

Questions related to resonance/standing-waves and sound

I understand resonance for a simple harmonic oscillator but not for more complex systems like standing waves. How can I be in resonance with the normal mode in an organ pipe? I understand that the ...
0
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1answer
43 views

Velocity change of objects

Is it possible for small object (small mass, let's say bullet) to hit large object (big mass, let's say rock) and still move forward (or stop) instead of being reflected (let's say objects don't crush ...
1
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0answers
81 views

Forces and acceleration due to an angle that varies over time [closed]

I'm having difficulty figuring out how to set a problem up. The problem is as follows: A $5\ kg$ block is being pulled along a frictionless floor by a cord that applies a force of constant magnitude ...
3
votes
4answers
690 views

Why can't the work done by a non-conservative force be zero?

Why can't the work done by a non-conservative force be zero? The displacement along a closed path is always zero. So, whatever be the type of force, variable or constant, the work has to be zero. Why ...
-1
votes
1answer
120 views

How do two rigid bodies with different 3rd moment of inertia rotate differently?

If rigid bodies $R_1$ and $R_2$ has exactly same total mass $M$, central of mass, and rotational inertia $I$, but different third moment of inertia $M_3$, how would they move/rotate differently? ...
0
votes
3answers
162 views

Why doesn't an orbiting body keep accelerating?

As a physics newbie I'm trying to get a grip on basic orbital mechanics. I think I'm beginning to get grasp on how bodies interact with each other. When a body approaches another body it accelerates ...
0
votes
1answer
29 views

Can $M_3$ move upwards and $M_2$ move to the right?

Can M3 move upwards and M2 move to the right? in the solutions they assume this, but I find it impossible, it doesn't make sense physically. I get the answer wrong if I assume M3 moving down and M2 ...
0
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1answer
37 views

Difference between short impact and sustained pressure

If I press the wall (with my hand) I feel a little pressure at my hand and I move away from it. If I hit the wall (lets say using the same amount of energy for total work) I feel pain in my hand. ...
0
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1answer
47 views

(air pressure and displacement) Isn't this image wrong?

Isn't this figure wrong? P(x,t) = -B(dy/dx) . If the derivative of air displacement has a maximum, then this is where the pressure is minimum, not maximum as this figure suggests. Could someone ...
2
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3answers
312 views

Why is Newton's first law necessary?

Newton's second law says $F=ma$. Now if we put $F=0$ we get $a=0$ which is Newton's first law. So why do we need Newton's first law ? Before asking I did some searching and I got this: Newtons first ...
2
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2answers
15k views

What is the relationship between Force and Kinetic Energy?

I am an Middle-School (Grade 8) student, who is self-learning classical mechanics. I saw this equation from Classical Mechanics: $\vec F=m \vec a$, the following equation is pretty straight forward ...
0
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2answers
32 views

How to cancel momentum without causing damage?

This is a fictional scenario I've designed and I'm trying to obtain a plausible logic for it to be somehow possible: I have a moving object, like a car or a person running, how can I stop it ...
6
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1answer
156 views

Will a rocket produce more thrust if fired in air, rather than vacuum?

I've been in an argument with a friend. He claims that when a rocket engine is fired in air, it get significantly more thrust due to the rocket pushing gas into the atmosphere, and the atmosphere ...
0
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2answers
348 views

Calculating velocity change after impact?

Let's say there is no gravity here and objects won't crush. We have 2 rocks with $m=10\text{ kg}$. First rock has velocity $v_1=0\text{ m/s}$ and second $v_2=10\text{ m/s}$ (flying in leftward ...