Questions tagged [torque]

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

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2answers
118 views

Centre of gravity: Adjusting position

If an object is freely suspended from a pivot, why does the centre of gravity fall directly below that pivot? Would this be the same in non-uniform gravitational fields?
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1answer
130 views

Work done by static friction during rolling while slipping?

I'm a bit confused on whether, during slipping while still rotating, friction does work on the object. I know there are multiple questions on SE that address the rolling case, but this is very ...
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1answer
34 views

Returning a seesaw to balanced

Suppose I have a seesaw that is tilted to the left because a force of 10N is being applied to it. While the seesaw is still tilted to the left, I apply a force of 10N to the right side of the seesaw (...
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Finding the torque on a square shape [on hold]

I came across this question when practicing rotational dynamics online. The answer is D, which is what you get when you multiply the forces by the distance to the center: $8\frac{\sqrt{2}}{2}-4\frac{\...
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2answers
25 views

How to find moment of inertia of complex objects?

Let's say we have a ring gear which is attached some mass and is supposed to rotate this mass. This gear is driven by another gear. How one can find the moment of inertia of the driven gear to ...
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3answers
5k views

What causes a rotating object to rotate forever without external force—inertia, or something else?

Someone told me that it is not inertia, but I think it is inertia, because it will rotate forever. In my understanding, inertia is the constant motion of an object without external force. Am I wrong?
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Equilibrium of a body in torque problem

I was watching a video about torque in which the task was to find the force $F_2 $ when a body is in equilibrium. The person in the video said that in order for the body to be in equilibrium, two ...
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1answer
123 views

Ratchet handle force calculation

I have strap ratchet which is being pulled on both sides with some force(say 500lb). Could some one please help me know the force to be applied on the handle of the buckle to open it? Can anyone ...
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1answer
25 views

Electric dipole torque problem [closed]

Problem 4.6 from Griffith's book: To solve it, we construct an image dipole $ \vec p_i$ with opposite polarity then find the torque $ \vec N = \vec p \times \vec E $ I'm having trouble knowing how ...
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1answer
139 views

Righting moment for object submerged in water

I am looking to determine the lateral angle at which an underwater camera system will no longer right itself. When on the ocean floor it is $-24.30~\text{kg}$ buoyant with the difference between its ...
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1answer
25 views

How would torque work if the force application point was extended with a handle?

When opening a door, the farther from its axle you push, the easier it is to open because you have more torque, now say at the far edge of the door (the edge that's not connected) there was a handle ...
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Torque computation for a “vertical”

How is computed the torque needed to turn a vertical circular mass ? Think about a wood circle (let's say 1m diameter, 2kg) with a motor fixed to it's center. The disc is oriented "vertically", like ...
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Moment (torque) problem [closed]

Why in this figure the total torque on object is not zero as one force cause the object to move in clockwise direction and the other force cause the object to move in anticlockwise direction ? How ...
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3answers
196 views

How is it possible to calculate the moment of inertia?

I would like to calculate the angular acceleration of an object on which a force $F$ is applied at point $P$. The scene is 2D, and the complex object consists of many axis-aligned rectangles. I ...
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1answer
25 views

Torque and angular acceleration in elliptical orbit

I am stuck in a supposedly simple aspect. Consider the Sun-Earth system. The torque is zero and angular momentum is conserved. $L = I\omega$ is constant, but since $I$ changes, $\omega$ should change ...
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1answer
17 views

Traslation of a bar on a plane - Contrasting results

I have a bar which can translate on a plane (gravity along y), at estremity A there are two forces and a moment, G is the center of mass, here I applied the gravity force: The dynamic equations are: ...
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3answers
67 views

Why do the inner tyres of a vehicle rise when taking a turn at high speeds?

When a person cycles at high speed on a turn, his body bends inwards, to raise the horizontal component of the normal reaction to provide the centripetal force for the turn. The more the speed is, ...
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4answers
786 views

Why does a car need more torque when accelerating from rest?

Since static friction helps in the movement of rolling motion, not opposes it, Why do we say we need more torque to get the car to move from rest if we have the rolling friction coefficient static ...
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1answer
225 views

Shear stress of a suspended sphere in a viscoelastic fluid

What I am trying to solve right now is that I have a magnetic particle (nanoparticle to be exact) floating in liquid that is viscoelastic and apply sinusoidal magnetic field. The applied magnetic ...
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2answers
329 views

Torque and force on a tire iron

So I was curious about something. Having a flat tire today and having to change my tire made me wonder. I understand torque and force are 2 different things though related they have separate ...
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0answers
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Moment about axis with force applied at non-parallel line

I understand the process to solve the moment of a force at a given point applied about an axis. However, what if the force was instead applied to a second, non-parallel? Perhaps a physical example is ...
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3answers
347 views

What will be the effect on a rigid body if two unlike unequal parallel forces act on the body?

What will be the effect on a rigid body if two unlike unequal parallel forces act on the body? Will the body translate or rotate or both? If they rotate, with respect too which point will they rotate?
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1answer
170 views

What will be the direction of the force required on the ball to move the ball up the stairs?

Is this diagram correct? The point of force A is at the farthest distance from the fixed centre O ,so the moment arm CD is greater and therefore,maximum torque would be produced.Is my concept correct?...
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How to choose origin in rotational problems to calculate torque?

We know that $\text{Torque} = r \times F$ and $r$ is the position vector. But the position vector depends on the choice of the coordinate system and in turn on the choice of origin. So, where should ...
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Can we add torques on different parts of body about a point and calculate total torque about that point?

Give proof also . I was doubtful as in a question . Torque due to a couple was calculated using adding torque of the couple due to different parts of the body .
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3answers
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Conceptual question about wheels

I am trying to understand quite naively wheels in a specific framework. Intro We normally think of squares and circles as different concepts of shapes, but I am reframing it that both are polygons ...
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How to consider a moment of a force as a 2-form?

My major is mechanical engineering. Recently, I'm reading "The Geometry of Physics An Introduction (3ed)" by Theodore Frankel. On page lix in the section O.r, the author discussed the concept of ...
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1answer
684 views

Angular momentum about a moving point

I was used to see the Angular Momentum Principle as: $\dot{\underline{H}_O} = \underline{M}_O^{ext}$ that is, the change in angular momentum equates the external torque w.r.t. a point $O$. Now, I'...
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265 views

The torque created using an oval chain ring

I have seen the explanation on "How bicycle gear works?" but this seem to be using a standard round chain ring. I would like to know if there is any difference when an oval chain ring is used. As I ...
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Isn't inertia experience by person in moving bus same as torque

When a bus moves suddenly, the person standing in it tilts backwards. This concept is explained using inertia(tendency of body to resist change in its state of motion) but when the bus moves suddenly, ...
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1answer
238 views

Torque of the contact forces about the centre of mass

A person leans in the opposite direction when he or she lifts a heavy load in one hand. I read a reason for the same in a book. According to the book, if a body is placed on a horizontal surface, ...
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2answers
592 views

How to calculate resisting torque due to moment of inertia

I'm trying to determine whether a motor is suitable for an experiment. I know the motor's torque and the moment of inertia of the disk it will be turning. I was able to find the angular acceleration. ...
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1answer
218 views

How to approximate this simple harmonic motion?

In the assembly shown in the figure, both the pullies are massless and frictionless on their axes. The positions of the strings are adjusted in such a way that, in equilibrium position, springs $k_1$ ...
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2answers
684 views

Why are non-horizontal levers not considered to be in equilibrium?

Consider a triple-beam balance, like so: (source: microscopesamerica.com) An unknown mass is placed on the left pan, and the provided weights are moved on the right until the lever arm comes to ...
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Conceptual Question Regarding Torque and Acceleration of a system

I have a quick question regarding a system with a pulley, a cylinder on an incline, and a block hanging down vertically from the pulley, all connected with a tension cord. IF the pulley has mass, then ...
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1answer
186 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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1answer
214 views

nutcracker in space, torque provided by thruster vs by reaction force

In the following image, a nutcracker is floating in space. Attached to points B and C are two thrusters (not shown). Each of them provides an equal force horizontally inwards, shown by the red arrows. ...
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1answer
411 views

Considering the theory of special relativity: Is torque still a vector?

Considering the theory of special relativity: Is torque still a vector? In classical mechanics it is easy: You have 3 axes and thus 3 planes. Every plane has its own torque so torque has 3 ...
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1answer
3k views

Line of action force

The task is to reduce the two forces into a single net force and then find the equation of its line of action. I chose to find the net force and momentum with respect to the origin. The magnitude of ...
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2answers
548 views

Influence of couple-moment's position on bending moment diagram

The moment of two equally opposing force would create a couple-moment. Since the couple-moment value is invariant to the point considered to calculate the couple-moment, I can replace the two equally ...
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1answer
268 views

Torque on rolling cylinder

Consider a rod with two equal forces acting parallel to the direction of velocity of a rolling rod, one at each end. When analysing problems involving torque, the choice of axis should not matter. ...
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2answers
259 views

How to spin a fidget spinner with maximum velocity?

Physics doesn't always come in the form of books. It also comes in the form of toys. So, I came across this fascinating toy that spins two minutes straight when given a spin. I got a chance to use ...
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1answer
117 views

Physical intuition behind torque converter

A torque converter (also here) is a device used in some cars. It uses several "fans" coupled through a liquid (transmission fluid) in order to perform the function of a clutch, but more importantly it ...
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What is the physics behind a pirouette?

Around last week, I watched a ballet production at the Melbourne Arts Centre, and boy was I amazed! These people dressed up in costumes were spinning on their toes in all kinds of ways, and I was ...
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3answers
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Why cars have transmission gears? [closed]

Cars need transmission to efficiently vary the speed of the wheels and this due to the fact that the internal combustion engines have a very limited torque band. What I don't understand is why ...
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Magnitude of moment in 3d space

What's the magnitude of moment about O, if the vectors F, r1 and r2 all lie in the z-y plane? I know the magnitude of the moment is the cross product of force and the perpendicular distance from the ...
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2answers
159 views

Why does the gyroscope not move upwards?

I have been watching a lot of videos on gyroscopes. Everything I see says there are two steps in gyro precession: Gravity pulls down imparting a torque The gyroscope moves forward It seems to me ...
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1answer
287 views

Angular velocity - Gyroscope

I am currently researching the gyroscope on my own and i came across the concept of angular velocity. The torque ($T$) on a gyroscope is caused by $R\cdot F$, where the force i consider it to be ...
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1answer
52 views

Friction in pulleys

The moment equation of a pulley with a rope applying tension on both sides is as follows: $$I\alpha = f + T_1R - T_2R$$ ( $I$ - moment of inertia; $\alpha$ - angular acceleration; $f$ - friction ...
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How is the rotation of a ferromagnetic bullet affected by a coilgun?

I've been asked a question that I'm unable to answer. It's about a coilgun, and even if it could probably be expressed in simpler terms, I'll ask it in its entirety just in case I make mistakes while ...