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Questions tagged [torque]

The tendency of a force to rotate an object about an arbitrary axis.

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Sine or cosine component of force on current carrying coil in a magnetic field

For calculating torque on a current carrying loop in a magnetic field, restoring torque that is, we use the $\tau=\vec{m} \times \vec{B}$ where $\vec{m}$ is the magnetic moment and $\vec{B}$ is the ...
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33 views

Forces on a Rotating Rigid Body

This question has been puzzling me for some days now and I thought I might ask you guys for some help. Say that we have a rigid body (like a rod) that is in a vacuum in space. Furthermore, say that ...
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Torque/Cross Product [duplicate]

Ok! My question is, what is the physical meaning of the vector produced by a cross product? For instance, in torque, what does the cross product’s resultant vector mean? What does it tell me about ...
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calculate the shear stress from surface traction

The problem is that I am simulating a hollow cylinder under torsion and I would like to compute the shear stress for it. The output of the simulation is the shear surface tractions. See the figure ...
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Moment of inertia and torque [closed]

Why there is different moment of inertia with respect to point P about which a rigid body is moving around a circle with some velocity and spinning about its own axis compared to the one which is just ...
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1answer
200 views

Difference between torque, moment and couple

I know the basics of them like Torque is force multiplied by the distance (from the point where there is no rotation like centre of gravity). Couple acts because of two equal and opposite forces ...
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35 views

Angular Velocity About Instantaneous Axis of Rotation [duplicate]

If you consider a cone of half angle φ rolling without slipping on a plane with angular velocity Ω as shown in the figure. What would be the angular velocity about the Instantaneous Axis of rotation? ...
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37 views

How do you sum up torques for a macroscopic object

Torque is measured about a point. But angular momentum for some object is measured around an axis. This doesn't make sense to me as in for example, a cylinder. If there are multiple tangent forces on ...
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34 views

Acceleration of The Centre of Mass of A Rod

The acceleration a of the center of mass of a system is equal to F/M, where F is the net external force and M is the total mass of all the particles of the system, or at least that is my current ...
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What are the horizontal forces on a heeling ship?

Consider the following image from Wikipedia: The article states: "Whenever a floating body in a liquid is given a small angular displacement, it will start oscillating about some point, called the ...
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1answer
106 views

Three Dimensional Torque on a Sphere

Assume that we have a sphere in 3D space. Let point $A$ rest on the surface of the sphere. I can apply a force $F$ of any magnitude and any direction, so long as it points tangential to the surface ...
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213 views

How can a magnetic field exert a torque that causes a disc to rotate?

I'm confused about the premise of this homework problem: A thin, non-conducting horizontal disc lies in the $x$-$y$ plane. The disc has a mass $m$ and a total charge $q$ distributed uniformly over ...
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86 views

Engine speed and flywheel [closed]

My doubt is about the third part of the question. I want to understand that if an engine is running at a constant speed, say 210 rpm, then can there be an acceleration in the flywheel? Because if the ...
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65 views

How much of an object's mass behaves as if it is located at the center of gravity? [closed]

We recently finished up a physics lab where a 200g weight was balanced at the end of a ruler on a fulcrum (measuring torque). In the analysis portion of the lab, we are asked: "How much of the mass ...
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82 views

Weight Distribution of a Heap of Logs

Suppose that you have a heap of logs. Each log is the same length $l$, the same mass $r$ , and the same radius $r$. For simplification, their rotational inertia is $I=\frac{1}{2}mr^2$, their ...
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2answers
60 views

The turning moment diagram of engine

In the engine, how is the force in the connecting rod Fg/cos(phi) , when the piston is not in static condition, but is rather moving forward? (https://i.stack.imgur.com/A0Bxi.png)
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Torque due to friction on a series of disks

Recently I was looking at two situations involving friction and torque. The first situation seemed pretty straightforward at first. A disk of mass $m$ and radius $r$, with a coefficient of static ...
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3answers
187 views

How did the Cavendish experiment to measure $G$ work?

I'm really confused about the Cavendish experiment. What I'm confused about is why the rod would oscillate around the equilibrium point. (From here on, I'm calling the balls at the end of the ...
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2answers
205 views

Torque, Angular Acceleration and Linear Acceleration

We know that we torque is applied, it cause an angular acceleration in the rotating body similar to what a force does to a body moving on a straight line. But my question is, Does Torque affect the ...
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3answers
148 views

Requirement for being in rotational equilibrium

An object in rotational equilibrium has no net external torque: sum of all external torques = 0 Does it mean "rotational equilibrium" may mean that the object is not rotating ... or it may mean ...
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1answer
63 views

Rotational work done

So the formula for rotation work is $$\mathrm dW=T\cdot\mathrm d\theta$$ where T is torque. While solving a question like in case of a body rolling down an incline (pure rolling), we usully equate ...
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202 views

What are the factors affecting torque (in normal cases)?

I know that force and perpendicular displacement are the factors. I want to know the factors like mass of the body and how and why is the force not distributed throughout the body uniformly. ...
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1answer
85 views

Why does a tidal bulge result in a net torque on the Moon?

I understand that a tidal bulge is caused because the side of the earth facing the moon experiences a stronger gravitational force than the other. This results in the oceans on that side slightly ...
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2answers
41 views

About which point should the torque be calculated? [duplicate]

While calculating angular acceleration in a problem, about which point should we calculate the torque and why?
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339 views

Torque on dipole in a non-uniform electric field [duplicate]

What happens when an electric dipole is kept in a nonuniform electric field?
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Why is torque sometimes reported in kg m, instead of the usual N m?

On various websites I see torque expressed as $\rm kg\: m$, but I was always thought that torque is $\rm N\:m$ or $\rm kg\: m^2/s^2$. These are clearly not the same, so why are they called the same, ...
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48 views

Translatory motion of a rod

For the translatory motion of a rod, shouldn't the torque about every point of the rod be zero? There is no rotation about any point right?
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70 views

Moment of Inertia of Infinite small rods! [closed]

Say we have a symmetrical and homogenous rod with mass $M$ and length $L$ and a rotating axis in the middle of the rod, dividing it into two halves. Its moment of inert is $$I_{cm}=\frac{M{L^2}}{12}$$ ...
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3answers
115 views

The direction of torque is so confusing [duplicate]

When I was studying cross and dot products, I learned that the cross product of two vectors A and B is perpendicular to both A and B. But my mind is unable to understand that. Since both A and B are ...
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1answer
41 views

Can't Determine the direction of rotation of a coil

Speaking of coils and torque here, So I have a coil and after I did fleming's right hand rule to get the direction of the torque (let it be the positive x-axis unit vector î can't remember it ...
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2answers
48 views

Clarify Torque and static friction [duplicate]

I came to this problem and solved it but I don't fully understand how this works. The problem is: A 200lb man climbs to the top of a 20ft ladder that is leaning against a smooth wall at an angle ...
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Mass is ignored in vector product of r(vector) and f(vector), why?

In this solution in the book, the mass is ignored after vector product of position vector and force vector. In both part a and b of the question it is the same. I was wondering what might be the ...
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1answer
34 views

How can I find the power given only the torque?

I have a system where I am trying to find the power generated by a DC electric generator. However, I am not very familiar with generators, so I am having difficulty determining the rotational velocity....
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47 views

What happens when you try to turn a gyroscope with high torque?

I apologize for my lack of basic understanding of gyro-physics, I tried looking up internet, but couldn't find any answer for this particular question. I have been told that if I apply torque to the ...
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2answers
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How to define signs for angular velocity, acceleration and torques?

I get confused how to define signs of angular velocity, acceleration and torques in the cases like the following. We have a disk with radius $r$ and center of mass at point $CM$ shifted $d$ from the ...
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1answer
36 views

In case of torque on sliding block on horizontal surface, why $y$ component of $\vec{r}$ is taken negative?

I've attached the picture above. In case of the torque on a sliding block on horizontal surface why r component is taken negative.
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1answer
38 views

Mechanics, Torques in accelerated frames

Consider the following problem: My first attempt of a solution was taking moments about Point O and solve for variables by setting the final torque to zero. After consulting the text book and quoting ...
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Rotor finds equilibrium in TWO positions, why and how?

I have a Mendocino motor, a toy with magnets, solar panels, and coils. Such a thing requires careful balancing (eg. with tiny bits of tape) to achieve sufficient balance that it will start rotating ...
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Why do doors turn?

I really think that I might be overthinking it but I was thinking about a door. When you try and open it with a force, it will produce a translational AND a rotational effect on the door. Any good ...
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2answers
69 views

Does torque provide rotation?

If a sphere is given a constant force along centre of mass, placed on a frictionless floor it does not undergo rotational motion as net torque about centre is zero. But why did we notice net torque ...
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130 views

Couple or torque

In the solution of Problem 527, over here, A homogeneous cylinder 3 m in diameter and weighing 30 kN is resting on two inclined planes as shown in Fig. P-527. If the angle of friction is 15° for ...
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1answer
44 views

Torque lesson in Physics

For the force on a current-carrying wire, Torque, was derived using the assumption that the cross-section area of the wire is constant along its length. Is this equation still valid if the cross-...
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1answer
31 views

Stability of a falling object

Suppose there is a falling object that has flaps around it providing resistance to the non-contact force of gravity. How would the vehicle theoretically not flip over? From my understanding, the ...
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1answer
116 views

The minimum diameter of a sphere such that a cone may balance on it [closed]

There is a solid sphere of diameter D, with a right circular cone placed on top of it. The cone has a height h and the diameter of the cone base is d, and d=h. Explain why the minimum value of D (...
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2answers
77 views

Torque equation about center of mass frame

Let say a uniform cylinder is rolling down an incline. Since the center of mass of the cylinder has non-zero acceleration, should it be considered as a non-inertial reference frame? I know that when ...
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5answers
132 views

Why is torque defined as $r × F$ and not $F × r$?

Is it merely due to popular convention or does it supply any special clarification regarding other physical quantities?
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1answer
67 views

Balanced Torques and centre of mass

Say we have a plank of wood that is placed on the edge of a cliff so that one end projects horizontally out over the edge. How would you go about finding the minimum mass that you could place on top ...
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2answers
78 views

Which way does a cylinder on a slab roll after the slab is removed?

An article by Tokieda[1] begins: I lay a cylinder on a sheet of paper. I pull the sheet from under the cylinder, briskly or gently. When the sheet is pulled out, which way will the cylinder roll?...
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How would I find the angular accelertion of a disk rolling up a ramp? [closed]

I need to find the angular acceleration of a hollow ball rolling (without slipping) on a ramp, given the angle of the ramp theta, the mass and radius of the ball, and gravity and other physical ...
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1answer
32 views

Force required for Angular Accleration

Suppose I have 4' x 4' piece of wood. Its mass is 150kg evenly distributed. I drill a hole right at a corner and place rod through the hole to create a rotational axis. I apply a tangental force at ...