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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Tension by a string on a pulley

I was doing this problem, and I had trouble drawing the free body diagram of the pulley. (The pulley is massless, frictionless.) I had trouble understanding how both the ends of the string will apply ...
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Two-body problem - falling into an object

In the two-body problem we can describe the interaction between two masses using the C.M frame and look at their relative position. The effective potential is then: $$ V_{eff} = \frac{L^2}{2\mu r^2} + ...
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How do you imagine the deformation of a body which has no ability to develop strain energy under constant force?

We know when any body is under a load, it undergoes certain deformation. To a certain extent, the body resists the deformation by forming strain energy. But, what if the material cannot develop strain ...
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Is the work derivation for torque valid?

Basically just the comment section of this answer here. I don't understand why energy should be conserved and not momentum. But I've also see this derivation in many places so I feel Like I'm missing ...
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Simple Moment Problem (High School Physics)

I'm not sure how to explain the effects of motion constraint for a high school physics problem that I'm helping my little brother with. The physics teacher sometimes includes "Bonus" ...
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Differential cross section and symmetry about an axis

I have a general question. Say we have particles with velocities in the direction of the axis of symmetry of a $3D$ body. I see in a lot of texts that in this case we generally consider the cross ...
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1answer
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Show that the initial speed of gun and the shell are in the inverse ratio of their masses

A shell of mass $m$ is fired horizontally by a gun of mass $M$ which is free to recoil and which is on horizontal ground. Show that the initial speed of gun and the shell are in the inverse ratio of ...
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Coupled oscillators - why is the order of $x_2 - x_1$ or vice versa the way it is?

In my physics class, we have been working on the two mass, three spring (coupled oscillator) problem and I found this great video that helps explain how to set up one of these problems. (Link: Coupled ...
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Torque on a spool of thread [closed]

Here is a problem I encountered in my physics class. I was thinking that the answer was a, but the answer key says that the answer is d. Could someone explain this problem to me and the concept of ...
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When I push an open door I feel less force but when I push a wall I feel a greater force

So I observed yesterday when I pushed a closed door I experience a lesser reaction force but when I push a wall I experience a greater force is it because of the fact while pushing an open door rate ...
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How does an increase in the drag force impact the drag coefficient?

After some derivation, the formula for the polynomial drag force constant equates to: $$ B = \frac{mg}{v_t^2} $$ Where B is the coefficient, m is the mass, g is gravity, and vt is terminal velocity. ...
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Conceptual Understanding of Rotating Block [closed]

I am asked to find the highest possible start $v_i$ such that the block will not go over the ledge. My first step is to apply conservation of angular momentum to get that $$L = \frac{1}{2}mvd=I\omega \...
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Ball rotating in a circle without rope/string - why doesn't the ball fall after the peak?

I am currently learning about the problem of a ball rotating in a vertical circle - where we are interested in determining the minimal height $h$ required in order for a ball sliding from rest down a ...
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5answers
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Why don’t we feel weightless on airplanes?

I was just sitting when suddenly I thought of something. If we feel weightless because there is no contact force acting on our bodies. Then why are there no contact forces for people in the ...
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An asteroid hits the Earth

An asteroid floating in space (about zero speed, not near any planet or star) has about zero gravitational potential energy. If that asteroid drifts near the earth, our gravity gives it some potential ...
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What is the relationship between amplitude and max velocity?

What is the relationship between amplitude and velocity? I read through my textbook and online, but I'm still unsure. For example, would an increase in amplitude be proportional to max velocity. If ...
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5answers
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Why I can't use $\mu N$ for solving the friction force of the rolling wheel?

Suppose we have a wheel rolling without slipping down an inclined plane, and we have to find the tangential acceleration of the wheel. The standard approach is to use the equation $$f\cdot R=(I\cdot a)...
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2answers
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How to determine maximum speed for a given bicycle gear ratio?

This question came up watching a final sprint at the Vuelta San Juan this year. One of the riders was sitting down in the sprint because he had "spun out" his gears, meaning there was no ...
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Kinetic energy at perihelion

How do you find the kinetic energy of an object (in orbit around the sun) at perihelion given it's eccentricity, the mass of the object and it's period?
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Confusion regarding centrifugal force

In this https://youtu.be/YCrFwQtW5o0 sir took a disk and demonstrated that the particles kept on it fly away due to centrifugal force. Now, suppose I take a ring in free space and a placed particle in ...
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When a car is coming to a stop is there any resistance offered by it to stay in motion?

Suppose a car is in a state of uniform motion moving at a high velocity and then begins slowing down due to force exerted by the brakes on the car. Will the car offer any resistance due to its inertia ...
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When is work done by static friction force positive and when is it negative?

So we say that a work done by a force is positive when both the force as well as the displacement of the body are at acute angles with each other. With this logic, consider a man standing on a plank ...
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How much work is done vertically? [closed]

How much work is done by a person who lifts a 4.00 kg block vertically at a constant speed up of 2.50 m/s through a height of 5.50 m? Can you show me the right process? This is how I did it. Em= Ek + ...
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Circular motion in a cone, velocity dependence of height

I'm attempting to solve the circular motion problem below: You spin a marble around the inside of a large funnel, such that it follows a circular path. How does the height $h$ above the bottom of the ...
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1answer
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Direction of rotation in Feynman's Wobbling Plate

For cube size 0.1,1,1, Mass=100; Initial angular velocity=ω(0)=[1;0.25;0.5]; we get Moment of inertia tensor=I=[16.67,0,0;0,8.42,0;0,0,8.42]; Angular momentum magnitude=|L|=17.32; If body axes=x’,y’,z’...
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Can you solve this exercise? It's really difficult for me? [closed]

I'm trying to solve a problem about mass center, but can't arrive at an answer. Any help would be much appreciated. The exercise states this: The shape of a butterfly's wing can be approximated ...
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How to write line integral to describe a force given in polar coordinates?

I have a force given by $\vec{F}=200N\cos\theta \hat{i}+200N\sin\theta \hat{j}=200N \hat{R}$ and I'm trying to figure out how to set up two line integrals to calculate work as a function of initial ...
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Question about period of a object attached to spring [closed]

An object of mass $0.9Kg$ is attached to a spring on a horizontal smooth surface. The object is put into motion. One side of the spring is attached to a wall and another side of the spring is attached ...
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1answer
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If you swing anything fast enough, can you nail a nail?

You have a nail set in a piece of wood for example. Theoretically if you swung something else at it, no matter what it was, could you drive the nail in, if it were moving fast enough. I get that the ...
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I don't know how to how to solve this question [closed]

Here, I am sharing a question from chapter: electrostatics of Mathew Sadiku . I have tried a lot to solve this question but I am not able to solve this question. I would be thankful if someone helps ...
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Concept on a ball on arena

So I was curious about how the free fall equations \begin{align} y &= y_0 - \frac12 gt^2\\ v &= gt \end{align} will get affected if, for example, a ball is dropped at free fall and touches the ...
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Calculate $e$ (coeff of restitution) if the ball follows the following path [closed]

The bottommost right corner is the ques. We have to find "e" After the ball follows that path. Both the walls have same coeff of restitution e. I firstly took out the total time by 2Uy/g ...
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1answer
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Derivation Of Rotational Energy From Kinetic Energy

I am studying rotation, and I would like to check that my understanding is correct. I am trying to prove that: $$ \tau \theta = \frac{1}{2} I \omega^2 $$ To prove this, let's consider an object that ...
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2answers
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Equations of motion of a catapult [closed]

I need some help with an incoherence in my results for the following exercise : A catapult consists in a massless beam of length $R + d$, that can turn around a fixed point O. A counterweight of mass ...
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2answers
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Equation motion of a material point on parabola through $\vec{F}=m\,\vec{a}$ [closed]

Consider a material point of mass $m$ that moves on a parabolic bowl $y=k\,x^2$, with $k>0$. In the reference frame of point: I have the following motion equations: \begin{align} \begin{cases} N-...
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Find the Work of a Particle Given Force Function [closed]

The force function on a particle is $F(x) = -Ax\vec{i} + Bx \vec{j}$ $(A = 3.76)$. The point travels from coordinates $(1,0)$ to $(1,1)$ then from $(1,1)$ to $(3,1)$. How much work was done on the ...
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1answer
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Calculate parameters of 2DOF mass spring damper system at steady state [closed]

I am given a task and I actually have answers. I think I know the way how it was solved, but I cannot understand why it is done like this. Task sounds as follows: Consider the below system configured ...
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6answers
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Mathematical Definition of Power [duplicate]

I am a high school student who was playing around with some equations, and I derived a formula for which cannot physically imagine. \begin{align} W & = \vec F \cdot \vec r \\ \frac{dW}{dt} & = ...
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1answer
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Why can we multiply by $dt/dt$ to change variable of integration? Please look at equation 5-20

I am struggling to understand why can we just multiply by $dt/dt$. I was thinking it was just a change of variables, but I cannot come up how that works. Can someone explain why we are allowed to do ...
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3answers
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Confusion about whether or not force can be exerted on air

If someone is running in air, the air exerts a force on them i.e. air resistance. However, does the person exert a force on the molecules in the air during their motion. It seems very likely to me but ...
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2answers
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Inertial and non-inertial frames

Firstly, I want to say that I realise that there are a lot of questions on inertial and non-inertial frames of reference, but the question I had in mind, no one seemed to have asked. I've just started ...
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What is the depth of the well? [closed]

how to cacluate a depth of a well when only given speed of sounds , and time until we heard the sound of the stone that hit the bottom of the well ?
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3answers
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Amount of work: clarifications

If to lift an object of mass $m$ a force greater than $mg$ is required then why do we take the amount of work done in lifting an object as $mgh$ could someone please explain that to me?
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Need help with block and pully [closed]

I was solving a block-pully problem(pully and rope are massless) and came up with a shortcut to find the tension($T$). I know its wrong but I can't find explanation for that. In the figure above I ...
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Relaxation times for springs with same spring constant but different lengths

I have two Hookean bead-spring dumbbells i.e. two beads separated by a Hookean spring. In both cases the spring constant is $K=2$. The beads have radius $a$. Dumbbell 1 has spring length $L_2 =2a$ and ...
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3answers
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Can the force on a single gate hinge ever be more than the weight of the entire gate?

This might be an obvious/stupid question, but it's been 20 years since my last physics class... Let's say I have a gate that hangs on two hinges. It weighs 40 kg, is 4 meters long and 1.5 meters tall. ...
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Which point the rolling ball will stop? [closed]

I don't know how to approach such questions. Please help me out. om/JE0C1.png
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1answer
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Numerical integration for simulation of rigid body using euler parameters

I am trying to numerically integrate the following equation of motion and solve for $\boldsymbol\omega $ vector(3x1) : $$\textbf{M} = [I]\dot{\boldsymbol\omega} + \tilde{\boldsymbol\omega}[I]\...
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“Inverse” $(N+M)$-body problem

This question is a logical continuation of the question about "Inverse" $N$-body problem. Let's consider the following extension of that problem: Assume that there are $(N+M)$ particles in ...
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Solving for minimum frequency in a circular motion problem [closed]

A 200g mass is tied on the end of a 1.6 m long string and whirled around in a circle that describes a vertical plane. What is the minimum frequency of rotation required to keep the mass moving in a ...

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