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 concepts, use [classical-mechanics]. For Newton’s description of gravity, use [newtonian-gravity].

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Reaction force of a rigid body sitting on an edge [closed]

How will the reaction force at A here be drown and why?
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Doubt regarding some overlooked steps when arriving at torque, in terms of Newtonian mechanics

The treatment of torque in most undergraduate introductory mechanics textbooks or pre-college textbooks assumes many things and doesn't explicitly state its assumptions. Torque is one such example. I ...
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How can we jump when the ground does no work on us? [duplicate]

This may seem like a silly question, but how can we jump when the ground does no work on us? When we jump off the ground, the ground does not move. This means the force from the ground on us does zero ...
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Generating a signal and idler photon pair from a TypeII SPDC

Many QM experiments use signal and idler photon pairs that are created by a non-linear crystal BBO. In the Wikipedia article https://en.wikipedia.org/wiki/Spontaneous_parametric_down-conversion the ...
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What is the electromagnetic linear momentum for a system of $N$ moving charges? [closed]

I am studying the equations of motion for a system of $N$ charged particles. When you add all the equations together, I understand that the sum of the Lorentz forces should be equal to the negative ...
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Mismatch regarding fictious force in this 2-body problem [closed]

Let us consider the motion in classical mechanics of a system of 2 particles #1 and #2 with masses m1 and m2 using vectors. The force between the particles is central force. There is no external force ...
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Why energy of a system equals to sum of its mechanical energy and its internal energy? [closed]

My books said that energy is a quantity that: Its variation equals to work done on system (1) It equals to sum of its mechanical energy and its internal energy (2) So, can (2) be inferred from (1)? ...
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Thruster force calculation for guided travel

I have a little 3D game where I control the forces I apply on a ship. I run the guidance program at regular intervals (100 times per second). I am having trouble coming up with maths to get my ship to ...
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What should I take as virtual displacement?

A bicycle rider has M. The wheels of the bicycle are at distance l apart and horizontal distance between the seat and the rear wheel is d. Use principle of virtual work to find the normal reactions on ...
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What is the relation between Newton's third law and law of conservation of energy?

Using newton's third law we can find law of conservation of momentum. $F_{12} = - F_{21}$ $\hspace{2cm}$ Newton's 3rd law $F_{12} t = - F_{21} t$ $\hspace{1.8cm}$ Multiplying by "t&...
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Direction of static friction in pure rolling up an incline?

Consider a simple situation where a round body is rolling up an incline plane and hence it is under the influence of gravity... My physics teacher says that to identify the direction of friction, we ...
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Standing up at 10% of the speed of light

Suppose I have a frictionless swing that is released from a height H m and I stand up after it has passed below the pivot at a height h m. If I stand up very quickly, say at 10% of the speed of light, ...
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Oscillation of cone on an incline [closed]

Suppose a cone is placed so that its slant height is parallel to the surface of the inclined floor. when i release it as it rolled down, the cone rotated back and forth around its vertex. What is the ...
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Velocity needed for throwing an object from one planet to just reach other planet [closed]

Two planets of masses $M$ and $9M$ but same radius $R$ is at a separation $8R$. Define the minimum speed required to throw a body of mass $1$kg from the first planet so that it is just able to reach ...
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Where would a string break if an instantaneous UNEQUAL tensile force is applied on the ends?

Similar to a question asked previously except this time with unequal tensile forces at the ends: Where would a string being pulled from both sides snap and why? Assume the string is homogenous. Would ...
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How does conservation of angular momentum not violate the time invariance of Newtonian mechanics?

Richard Feynman states: This follows from the fact that if we substitute −t for t in the original differential equation, nothing is changed, since only second derivatives with respect to t appear. ...
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How to determine the extension of a spring?

The spring extended by $x\ m$, and the object moved downward from the mean position due to the force of gravity and reached an equilibrium. Find $x$. My attempt: I used a free body diagram to find $x$:...
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Does horizontal acceleration affect gravity?

If we apply 1G horizontally in some object, will this constant force equal to G affect the time of falling? If the force does not affect gravity, why gravity is prioritized over this force if both are ...
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Objects on inclined planes and the normal force [closed]

Say we had an object lying on a inclined plane, at an angle of $\theta$ to the horizontal, and the object has a mass of $m$. If we take the obejct to have an acceleration of 0 perpendicular to the ...
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How can I design a gearbox for a stepper if my priorities are to convert step angle from 1.8 to 0.1 degree steps while maintaining high torque? [closed]

I'm using a NEMA 23 stepper motor for azimuth solar tracking, now since 1.8 degrees step angles are too large, I need to decrease the step angle as much as possible while maintaining as much toque as ...
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What Bell states do apply to entangled electrons?

Electrons are fermions with spin $\pm \tfrac12$ obeying the Pauli exclusion principle. Is it then correct to conclude that only the wavefunctions of the two Bell states $|\Psi+\rangle$ and $|\Psi-\...
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Masses/spheres on a ring

Suppose I have a ring of radius R. And at the COM, two point masses of equal mass are placed. They're connected to the circumference with 2 massless rods such that they can move freely on those rods. ...
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The concepteul understanding of such mechanics [closed]

can someone explain this situation intuitively? A guy who's mass is m1 standing on a wood which plane mass is m2 pulling him self up pulling each side of the rope with power F. Except those masses, ...
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Question about period and frequency

In the context of uniform circular motion, I have been so informed that period ($\tau$) is properly measured in seconds; and that frequency ($f$) in inverse seconds. Why is this the case? Wouldn't the ...
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How can the Joule be the unit of both work and energy?

Say a person applies 1 N to a box with a mass of 1 kg, displacing 1 m. This is one Joule of work (1 N for 1 m). Now say the person applies 1 N to a box with double the mass, displacing 1 m as well. ...
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What type of spring system can this system be treated as?

As we all know that when the springs are connected in series the tension is same throughout spring system collectively (elongation may differ in each spring if the spring constants of each spring are ...
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Why don't we feel centripetal force as we move from the outside of orbit to the inside?

In a debate with a flat earth friend and need help to make sure I understand this correctly. He points out that the part of earth that is on the outside of its orbit is traveling faster than the ...
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Work-energy theorem and Newton's second law

I was going through a book in which it was written that 'Work-energy theorem for variable force, in general, does not incorporate the complete dynamics of Newton's 2nd law of motion as the theorem ...
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Frictional Force Acting On A Walking Dog

Recently I came across a free-body diagram that confused me. It is a dog attached to a leash that is held above and to the left of the dog. There is friction between the dog and the ground, however ...
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Forces acting on blocks attached to a pulley moving in uniform circular motion on the horizontal surface from an inertial frame of reference [closed]

A table with smooth horizontal surface is placed in a cabin which moves in a circle of large radius R with uniform angular velocity. A smooth light pulley of small radius is fastened to the table. Two ...
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Rotation about a fixed axis

"If a body is rotating about a fixed axis passing through its centre of mass, then net force on the body is zero. In this situation it is possible that angular velocity of body is variable." ...
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Cantilevered object with support rope at free end; do rope tension & other forces increase at angles below 45 degrees to horizontal & how?

Cantilevered objects often require rod/rope support at the free end, as sometimes seen on shop signs or door canopies / porches bolted to the lintel area of a wall. If a supporting rope is vertical it ...
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Orbital motions

Suppose two satellites are moving in circular orbits around the earth and then crash into one another. My Question is this, how do we know that the bodies move in an elliptical orbit after the crash? ...
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Vector Form of strain Compatibility

I was reading the book called energy principles and variational methods in applied mechanics-J.N Reddy. In that I came accross this ∇×(∇×ε) = 0 notation for strain compatibility equation. I understand ...
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Why is momentum not conserved in some cases? [closed]

The total momentum of a system must be conserved, but in some cases I can't figure out the problem that makes the momentum not mathematically conserved. So, here's an example. When the small bullet ...
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Equation for position and velocity of a body falling in a gravitational field [duplicate]

I have tried asking this question on many forums and have so far failed to get a clear answer. Here is the problem. A body with a negligible mass is falling from a distance $R_1$ in a gravitational ...
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How to solve it? [closed]

Fan of a remote operated model helicopter of mass $m$ has diameter $d$. Denoting density of air by $\rho$ and acceleration of free fall by $g$, deduce expression for the minimum power required for ...
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Distance a block slides along a surface with friction given with an initial velocity [closed]

For this part (e) of this problem, Source: https://ocw.mit.edu/courses/8-01sc-...647ea989a352a972dc4b3dfe_MIT8_01F16_pset7.pdf The solutions are, However, I don't understand why they only used a ...
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Disparity in number of nodes observed in Tranverse and Longitudinal waves in Melde's Experiment

In Melde's Experiment, why is the number of "loops" observed in transverse setup is double of the longitudinal set up? I don't see how there should be a difference. In the case of the ...
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Scenario on the sign of hooke's law

Doubt is on the concept of the sign, not on the problem itself The main doubt is focused around the sign of $\vec{F}=-k\vec{x}$, and yes I've read a lot of posts on this page but it never ceases to be ...
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Motion under constant acceleration, is the proof correct?

The first result in physics texts is the distance travelled under constant acceleration $a$ and initial velocity $v_0$ is given by $$x=x_0+v_0t+\frac{1}{2}at^2$$ This can be proved by calculating the ...
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Sign of the hooke's law force on this case [duplicate]

Doubt is on the concept of the sign, not on the problem itself The main doubt is focused around the sign of $\vec{F}=-k\vec{x}$, and yes I've read a lot of posts on this page but it never ceases to be ...
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What is the role of rheonomic constraint?

Suppose we have a slipping mass on a rotating leg but pointing under the horizontal plane with a controlled angular speed $\omega$ depending on time, what about the number of degrees of freedom, ...
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Mass of a body that safety belt belt can accept. (Fmax=1500N, Mmax = ?) [closed]

There is problem where a car is travelling 20 m/s and inside of the car, there is a body with mass of 70 kg. Body is tied up with a safety belt to the seat. Safety belt can accept 1500N of force. What ...
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Is Earth's surface gravity termed $g$ derived from Newton's universal law of gravity?

Trying to apply the basic Newton law $F = m a$ to a falling apple and a paper clip I encountered a problem I consider a beginner's: The fact that all objects are subject to the same acceleration ...
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Can we prove that a constant central force pointed towards a point produces circular motion?

I was analysing the motion of a body when a single, radially inward force acts on a body, and I was trying to prove this is indeed circular motion, using geometry and looking at what happens at ...
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Intuitive understanding of the unit $kg/s^3$ — the unit of sound volume

I know that decibels are used to measure volume of sound, and they are basically a logarithm of $kg/s^3$. The best explanation that I have for the unit of $kg/s^3$ is that it is an alternate way of ...
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Why can the coriolis force potential be written as $ E_\text{cor}=m\dot{\theta}\begin{vmatrix} X & Y \\ \dot{X} & \dot{Y} \end{vmatrix}$?

I found the following formula for the Coriolis force written here: $$ E_\text{cor}=m\dot{\theta}\begin{vmatrix} X & Y \\ \dot{X} & \dot{Y} \end{vmatrix}=m\dot{\theta}\ (\dot{Y}X-\dot{X}Y)$$ I ...
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Why is it proclaimed for astronauts to be "falling"?

My physics teacher explained that the reason why it looks like astronauts are floating is because they are "falling". However, the way I think of it is that the outwards inertial force of ...
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A simple but not easy problem: Describe free motion of a stick [closed]

Assume there is an ideal rigid stick $AB$. We apply a force $F$ with constant magnitude at the end point $A$ of the stick, with $F$ and $AB$ always perpendicular to each other. Note that the motion is ...

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