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Questions tagged [torque]

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

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Torque contacts

I experienced yesterday that when the slotted screw driver head was exact fit to the slotted screw, it was easier to turn the screw. I'd like to understand the physics of it. Is the bottom easier to ...
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21 views

Finding force exerted on a turbine blade by water flow

I am trying to find the maximum theoretical rotational power of a turbine from the following quantities: $\omega$, $r$, $\gamma$, $I$, and $t$. This is in an experimental setting, not an assignment,...
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Finding force from torque equation

I have read an article on electrostatics textbook that, $$\vec {F}= \nabla {\vec {\tau} }$$ Such as,the toraue equation on a magnetic dipole is $$ \vec\tau={\frac{{\mu}_0 m^2}{2\pi z^3} }\hat{z} $$ ...
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How do I draw a diagram of the forces that create the “barndoor effect” (unbalanced torque) in rock climbing?

I have been asked to use a diagram that illustrates when a flag in rock climbing is necessary. I have no idea how to draw the forces involved in torque.
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Determine the torque of a rotating cylinder [closed]

I'm working on a homework assignment and seem to be stuck. The question is as follows: I started off by calculating the magnetic dipole moment of the cylinder first and ended up with something ...
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1answer
48 views

Newton's third law for rotating systems

As often happens for the rotational world, the Newton's law can be restated in terms of angles, moment of inertia and torques replacing displacements, masses and forces (this is one source among ...
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Why the angular velocity in DC MOTORS = 0 when torque is maximum?

Why the angular velocity in DC MOTORS = 0. when the torque is maximum. is it supposed to be maximum with angular velocity and torque in the same time!
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Pushing Two Balls Into One Another [closed]

Say for instance you have two tennis balls. Placing one on the table, hold the other in your hand and have it touch somewhere between the side and top of the other tennis ball. Now, when you start to ...
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3answers
43 views

How can Torque act on an electric dipole if an electric dipole is not a rigid body?

According to my knowledge of physics, torque can only exist on a rigid body and an electric dipole is defined as a "system of charges" (equal in magnitude, opposite in sign) separated by an ...
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59 views

Is it possible to show that calculating the torque using the center of gravity results from an integral?

We assume that the object's density is the same everywhere, and that indeed has a perfectly rectangular shape. We also assume that its volume is continuous and dont work with particles here. To ...
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1answer
19 views

Deriving the equality between the external torque and the rate of change of angular momentum, for a system of particles

I've started working through Analytical Mechanics for Relativity and Quantum Mechanics by Oliver Johns and I'm stuck on deriving a formula. In the section titled "Change of Angular Momentum", Johns ...
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22 views

Pure rolling of cylinder with arbitrary inertia

I'm having trouble understanding how pure rolling is possible for cylinders with arbitrary inertia and arbitrary torques applied to them, because it seems that the reaction force doesn't necessarily ...
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2answers
25 views

Rolling w/out rotation Yo-Yo (torque)

given a Yo-Yo that is rolling on the floor without slipping: why is the total torque equals to T*r+F_friction*R=I*w rather then -Tr-F_frictionR=I*w ive set the ...
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1answer
41 views

Resultant force from two lever arms held together at a fixed angle, weight hung on one arm

Trying to determine the resultant force F with the setup pictured below, given that L1, L2, and theta can vary. Not sure how to translate the torque applied by the weight to the force at L1. Thanks in ...
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1answer
33 views

What is the force on a dipole in a uniform electric field?

For an electric dipole of dipole moment $\vec{p}$ placed in an electric field $\vec{E}$ experiences a force given by $$\vec{F}=-\nabla U=-\nabla(\vec{p}\cdot\vec{E})=(\vec{p}\cdot\nabla)\vec{E}.$$ So $...
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Torque and angular acceleration , moments , counterweight

As mentioned before i am from a mechanical engineering background trying to design a product using counterweight. I was thrown into confusion regarding torque and moment even after doing my own ...
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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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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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1answer
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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
43 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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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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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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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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3answers
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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
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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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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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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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2answers
58 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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1answer
73 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
52 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
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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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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
99 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
55 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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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
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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
40 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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1answer
107 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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1answer
33 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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68 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
101 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
19 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
36 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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38 views

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
33 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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1answer
44 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 ...