Questions tagged [newtonian-mechanics]

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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Does a car use friction to move?

When a car's engine injects fuel into the cylinder chambers, the reaction creates a force that generates rotational momentum to the shaft and over the transmission, it translates that power to the ...
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1answer
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Does changing the angle of a pendulum also shift the coordinate plane w.r.t which we give rectangular components to the $mg$ vector?

So given a simple pendulum, which makes an angle of 0 with the vertical axis in it's resting position.Now the pendulum is moved to a side by an angle $\theta$ with the vertical axis. The components of ...
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1answer
89 views

Newton's third law in magnetic in magnetic fields

Say I have a charged particle moving through a magnetic field perpendicular to it. It will experience a force, but according to Newton third law Every force has an equal and opposite reaction. So ...
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2answers
178 views

Is the equation of motion for a spring-damper system the same whether oriented upward or downward?

So every spring-damper system I've found online has the equation of motion: $$mx''+cx'+kx=0$$ I can understand how this is derived when downwards is positive, but what about when upwards is ...
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3answers
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Will a body accelerate forever in space?

This is confusing. I have often heard that energy is conserved and it neither be created nor be destroyed. But, if a body is accelerated in space, neglecting every celestial body, it would never stop ...
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2answers
153 views

Oscillation of elastic rope hanging from the ceiling

I have to explore the problem of oscillations of an elastic rope hanging from the ceiling, which can move both in vertical and horizontal direction. I'm planing to solve this using a finite ...
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0answers
34 views

Noether's theorem with Newtons's approach

I know Noether's theorem can be applied to symmetries of the action, which is defined within the Lagrangian approach to mechanics. However, does the same theorem still apply if I use a Newtonian ...
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1answer
202 views

Torque and Conservation of Angular Momentum

I am having a conceptual understanding with the law of Conservation of Angular momentum and when it holds. Wikipedia says: "In physics, angular momentum (rarely, moment of momentum or ...
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2answers
123 views

Friction during ball backspin and overspin

I already know sliding friction of ball on a flat table and rolling resistance of it. How do I know coefficient of friction value when the ball has backspin with some angular velocity $\omega$? And ...
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0answers
32 views

Reference Request: Physics 1 for people who already know the math [duplicate]

I'm a Statistics undergraduate student and, this semester, I took a Physics 1 (Mechanics) class. The physics in this class is really just high-school physics but with basic Calculus and some Linear ...
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2answers
176 views

Why does the direction of a Foucault pendulum change if its axis is not parallel to the rotation axis of the Earth?

Let's say I'm in the US and I create a Foucault pendulum. Why does its direction change if its axis is not parallel to the rotation axis of the earth? I can understand why it changes if it's at the ...
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2answers
205 views

Simple harmonic motion..direction of acceleration

To solve questions about simple harmonic motion, my book says $\ddot{x}$ (i.e. acceleration) is in the direction of increasing $x$, i.e. away from equilibrium. I don't understand why is this so, since ...
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1answer
275 views

Falling and sliding object

I'm trying to model a particle being dropped from a height onto a smooth inclined ramp, sliding down it and then freely falling after it leaves the ramp at the bottom (no friction or air resistance). ...
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2answers
888 views

If displacement is 0, why isn't the work performed on an object 0?

Work is force x distance/displacement. The exact definition is something I'm a little confused about since my professor said it could either be distance or displacement. So going with that, if the ...
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2answers
71 views

Do internal forces always act along the line joining the particles?

For the rate of change of angular momentum of a system to be equal to the torque due to external forces, the torque due to internal forces should be zero. This will mathematically be possible only ...
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4answers
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How did Newton discover his third law of motion?

How did Newton discover his third law? Was it his original finding or was it a restatement of someone else's, like the first law coming from Galileo? What initiated the concept of what is now known as ...
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8answers
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Doesn't the work $W = \int F \, dx$ count only the work done by the outermost point of a spring?

When we use the integral to calculate the work done by the spring force, then according to my interpretation, we are only calculating the work done by the outermost point on the spring. Why don't we ...
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3answers
46 views

Centripetal acceleration on frictionless plane

Suppose I have circular, frictionless disk, and in the center of the disk there is a small box. The disk is then rotated. I gently push the box to disorient it from the center. Will the box accelerate ...
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3answers
662 views

Derivation of yaw, pitch, roll equations for an accelerometer

I'm struggling to find a good resource that explains how roll, pitch, yaw angles are calculated from the X, Y, Z measurements of an accelerometer. I came across this document but the explanation on ...
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2answers
190 views

Experiment in dynamics/newton's laws

During my physics class the teacher demonstrated an experiment to us: The teacher said that if we pull the rope slowly than the rope will tear at connection A, but if we pull the rope instantly/with ...
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10answers
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Does centrifugal force exist?

Currently in my last year of high school, and I have always been told that centrifugal force does not exist by my physics teachers. Today my girlfriend in the year below asked me what centrifugal ...
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2answers
72 views

Discussion regarding work done? [closed]

Suppose I take a box with some masses and pull it along the table at a constant speed. In this case, there is a force pulling to the right (the string) and a frictional force pulling to the left. ...
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2answers
43 views

Discussion - Why will an object move downwards inside a rocket moving upwards?

Suppose a rocket is launched upwards , and an object (say on the top of the rocket, inside the rocket) is at rest. If i'm correct , as soon as the rocket starts moving upwards , the object would ...
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1answer
54 views

Does friction depend on velocity?

I wanted to ask why (how) friction on wet surfaces and friction on dry surfaces have different velocity dependence?
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2answers
39 views

Need of describing the term acceleration [duplicate]

What is the need of acceleration when we have velocity As I think velocity as 1m/s means 1m covered in 1s and 1m/s^2 means 1m covered in 1s per 1s this statement creates confusion when it comes to ...
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2answers
56 views

What is the need of acceleration? [closed]

As we can usually predict the various forces that a body might be undergoing based on its position and its velocity.Hence what is the need of acceleration?
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1answer
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Understanding the geodesic equation in a Wikipedia article

I was reading this Wikipedia article which attempts to motivates some concepts key to General Relativity in the Newtonian setting first. However I was not able to understand one of the equations ...
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1answer
31 views

Why are you accelerating yet remaining at a constant speed while going around a curve? [duplicate]

We have to write a rap in physics, and it has to answer a prompt he gave us on this packet. The prompt for the verse I am writing is: Pretend you are driving a car on the freeway going 65 mph. The ...
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1answer
25 views

Direction of friction in pure rolling

Suppose a disc or a sphere with uniform mass density is purely rolling without any slipping/sliding on a ground having friction. Will there be friction acting on the disc/sphere? If yes, what will be ...
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1answer
62 views

What is the true quantitative definition of “force”? [duplicate]

Newton's second Law of Motion states that for a point mass, $\vec F = m \vec a$. This is a law and not a definition. So, this law only makes sense if all the physical quantities appearing in this law ...
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1answer
253 views

Displacement of string and simple harmonic motion

If the displacement of a string follows $$ y(x,t) = A \sin(kx - \omega t + \phi_0) $$ how can I show that the "hand" generating the wave must be moving vertically in a simple harmonic motion? ...
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1answer
19 views

Angular velocity in Body-fixed frame and space-fixed frame

When we solve for a free symmetric top we find that in body fixed frame, the angular velocity precesses. My confusion is regarding the calculation of omega in body frame. When i am in the body fixed ...
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0answers
40 views

How do you calculate how heavy you feel from negative g forces? [duplicate]

My physics tacher told me that to calculate the weight that you feel from negative g forces you have to devide your mass by the negative g force, but then my friend told me that it did't make sense ...
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1answer
36 views

Why is resultant displacement in an composition of simple harmonic motion the sum of individual displacements?

I recently came across the concept of the composition in simple harmonic motion. A paragraph says that: If $$x_1 = A_1sin(\omega t)$$ $$x_2 = A_1sin(\omega t + \phi)$$ Then, the resultant ...
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1answer
90 views

“Newtonian limit” property of special relativity

Books say that special relativity is indistinguishable from Newtonian mechanics when the speed of the primed frame ($v$) is small compared to the speed of light ($c$). This is what I mean by the "...
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3answers
853 views

Can you get a playground to swing from stationary

I feel this might be a FAQ but I would love a definitive answer. Imagine a frictionless stationary idealised child's playground swing. If you are sitting on the seat of the swing, is it possible in ...
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1answer
56 views

How much weight do you feel during negative g-forces?

My physics teacher told me and some other students that when you experience negative g-forces, your weight equals: $$\frac{mass}{g_{force}}$$ So when the g-forces equal -4 g your mass will be: $$\...
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0answers
40 views

5 Lagrangian points: why isn't there a line of stability between $L_1$ and $L_4$ and $L_1$ and $L_5$ respectively? [duplicate]

Given the 5 Lagrangian points of two large orbiting bodies: (from wikipedia), why isn't there a line of stability between L1 and L4 and L1 and L5 respectively (as depicted in red in the modified ...
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1answer
23 views

What is the definition of the “characteristic radius”?

Upon solving exercises regarding relativity, I have run into the problem below. The inverse square radius of curvature of spacetime is of orer the tidal field, $R^{-2} \approx \nabla^2 \phi$ where $\...
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1answer
119 views

Torque exercise problem

I am learning physics with help of this site https://www.khanacademy.org/ And I have stumbled upon a task that I can not completely understand The task says: A gasoline engine producing Nm of ...
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2answers
851 views

Is “Total Energy = Kinetic + Potential” always true in a harmonic oscillator?

Consider a object executing simple harmonic motion in one dimensions due to a variable external force (like a spring maybe). I like to think that at any point in it's motion at any time the mechanical ...
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1answer
66 views

Feynman screwjack problem

What is a thread? How does he know you need to turn the handle "around" 10 times? From where does the 126 inches come from? I thought Feynman explanations were easy... Let us now illustrate the ...
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2answers
157 views

So, DO All Things Float In Space, Or Not?

Incredibly, I cannot find an answer to this anywhere. The experts say that planets etc don't actually float in space, but instead continuously 'freefall' around the object they're orbiting and so on. ...
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1answer
33 views

When two people are pulling a rope, how come the force at the center of mass of the system(the tension on some specific point at the rope) is not 0?

Imagine two people of equal mass are pulling a rope in different directions. At the midpoint on the rope, why is the force acting not equal to 0? Its the same issue if I hold two newtonmeters, attach ...
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1answer
118 views

Why is this system isolated (revised)?

(Image updated for clearance) Hello, Assuming that there is no friction anywhere and both box 1 and ramp 2 start at rest, I was wondering why this is an isolated system in terms of momentum ...
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1answer
203 views

Feynman screw jack device

Feynman mentions in his book, The Feynman Lectures on physics Let us now illustrate the energy principle with a more complicated problem, the screw jack shown in Fig. 4-5. A handle 20 inches long ...
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3answers
178 views

How to conceptualize Newton's apple?

I have no physics background, which is the genesis of my question. In pop-science, it is frequently mentioned that Newton's apple didn't fall toward his head, but rather that his head came up and ...
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6answers
13k views

Can you ever exert more downwards force than your weight?

So, because I'm a hardcore person, I risked all this afternoon by going out in the wind, the rain and the cold to construct a willow den. Yes, it seems a menial task, but it was actually quite ...
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3answers
279 views

Newton's Third Law in an elevator

Some misconception I'd like cleared up. From what I understand, when an elevator accelerates downwards with you, there must be a net force acting downwards on you. Since your true weight remains the ...
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6answers
7k views

Why doesn't Newton's third law mean a person bounces back to where they started when they hit the ground? [closed]

Why doesn't a person bounce back after falling down like a ball does? If we push a person and he falls down then why doesn't he come back to his initial position? According to Newton's 3rd law of ...