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Questions tagged [torque]

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

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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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2answers
54 views

Centre of Mass and Reference Point

When calculating the centre of mass for a small body compared to the earth, the equation $$\vec r_c = \frac {\sum_i m_i \vec r_i} {\sum_i m_i}$$ is used, where $\vec r_c$ is the position vector for ...
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1answer
119 views

Ideal rolling with friction - torque perspective [closed]

So, let's take the situation where a perfect cylinder or ball is rolling, without slipping, to the right. The ball is rolling clockwise from our perspective viewing it rolling to our right. There's a ...
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1answer
39 views

relation between input and output torques for a geared machine

what is the torque in both ends of this gear set ? thanks! Multiple speed gear paradox box https://www.youtube.com/watch?v=bIMDtkm_ENQ
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4answers
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What does it mean for a force to “go through the center of mass”?

In Chapter 19 of Feynman's Lectures on Physics, Volume I, it says ...where can we apply a single force to balance the gravitational force on the whole thing, so that the entire object, if it is a ...
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1answer
159 views

How to decide the axis of rotation? [closed]

The question The Solution Part (c) is where I have a doubt ... How do I approach such problems? They way I approached such problems (and most of them had sufficient friction so that that the ...
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2answers
167 views

Explain translation and rotation in empty space

There is a previous question of mine which asks about rotation in empty space. Please look at previous question for greater understanding of this question. Explain rotation in empty space My ...
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2answers
838 views

Varignon's theorem (Principle of moments) failure?

Varignon's theorem states that "If many coplanar forces are acting on a body, then the algebraic sum of torques of all the forces about a point in the plane of the forces is equal to the torque of ...
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1answer
98 views

What is the physical meaning of torque about an axis outside the body?

Suppose for example that we have a ladder in space and it has zero translational motion, but non-zero rotational motion and non-zero angular acceleration around its center of mass. The ladder is ...
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1answer
330 views

Torque exerted by pressure in a fluid

If I have a solid rigid body (let us call it a duck) in a static regime submitted to the forces of pressure $P$ of a fluid (no shear forces) I can easily calculate the total force $\mathbf{F}$ exerted ...
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1answer
66 views

Why do two bodies affect each other with the same but opposite torque?

Update: After further reading, it looks like the torque $C_{12} = C_{21}$ should not be seen as caused by the force $F_{12} = -F_{21}$. The resulting force at the contact point causes an independent ...
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Moment around an axis vs moment around a point

So far i've seen two different approaches to find the reaction moment (torque) in a machine or constructions. The first method is to apply the classic definition of torque by choosing a reference ...
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2answers
126 views

How to nullify effect of Centrifugal force/centripetal force

I have a track over which a rectangular object moves. The object holds sensitive material which should not move too much. Then there is a 90 degree turn of the track with some radius of curvature. ...
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2answers
1k views

Is there a possible solution here to who carries more weight?

I am usually skeptical of riddles online that have to do with Physics but this one struck me as they had an oddly specific answer to it. So my question is for the following picture: I simplify a bit ...
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1answer
75 views

Need help in calculating the pull on string in kgs when moving weight on horizontal bar

need your help. I realized today, if you do not practice it becomes hard to understand simple concepts even you were once a science student :( I have attached a picture to help make the problem ...
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1answer
92 views

Is there a contradiction with the frictional force acting on a rolling wheel on a flat surface, if you consider both the net force and the torque? [duplicate]

I have had a physics problem on my mind for a few days and it seems relatively simple at first, but it has been puzzling me, and I was wondering if you could help. Say a student rolls a tire on a ...
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2answers
221 views

Torque Equation for a point other than the axis of rotation [duplicate]

I am having a problem while dealing with the so called torque equation τ=Iα, which I am describing with the help of an illustration. Please help me out. Consider a rod of length L and mass ‘m’ lying ...
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2answers
86 views

Why do cars steer the way they do? [closed]

I'm not sure if this is the correct site to ask, because I could not find other site that suit better. Consider this picture The top-state is the car when wheels are straight. I found on the Why ...
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2answers
95 views

Where does the torque force come from? [duplicate]

If there is an object which is $10 kg$, and we apply a force $|\vec F| = 100N$ then it will accelerate in the diraction where the force vector points with $10 m/s^2$ If the mass center is at point $O$...
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3answers
1k views

Is it possible to apply a torque without a moment arm?

In some statics problems, the question may say something like "a torque is applied about Point B". I've always assumed this was a simplification and the torque was created using a force and a moment ...
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0answers
22 views

Static Equilibrium: cable sag considering equal pulling forces on extremities

When considering a cable with a non-negligible mass and an equal force pulling the cable at both extremities, how can one compute the mid-span sag or a sag function whilst accounting for this pulling ...
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1answer
54 views

What does $T$ in the following notation signify? $F = (F_{rot}, F_{tran})^T$? - 2D Car rotation physics [closed]

I am reading the following paper to help me understand 2d car steering physics. In several places the paper shows a notation where a vector is put to the power of $T$. Like so: I am assuming it is ...
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2answers
74 views

Power in 1st Gear

The max power an engine puts out is what determines the max speed a car travel at right, obviously it's more nuanced than that because there are losses in the drive train, and the shape of the car ...
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1answer
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Free Body Diagram Errors

Click to zoom picture: Why is the force acting down on the hand only $\vec{F_g}$ ? Shouldn't it be $\vec{F_g} + \vec{N}_{object, hand}$ ? Since there is a normal force acting down on the hand from ...
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37 views

Torsion and Internal Torques of a Stepped Cylinder

I am having some difficulty reconciling what my solution manual says and what I calculating. I would appreciate a peer check on the following. The problem is described by a stepped cylindrical rod ...
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1answer
52 views

Plane rotation of a bar in a viscous fluid, computation of the torque

Assume a rigid, cylindrical bar which rotates around $\Omega$ (axis of a engine). The bar is immersed in a fluid of kinematic viscosity $\nu$ and has a plane motion. What is the torque applied to ...
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4answers
185 views

The nature of Torque as a vector

I can’t comprehend torque’s role properly: 1: What is torque’s nature? Is it some kind of energy? Because its unit is (n.m) and (n.m) is similar to (joules) and it’s energy unit. 2: As we all know “...
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1answer
33 views

Wheel size for climbing up on inclined surface

I am going to make a Line follower robot which can climb up on a inclined bridge(45 degree with flat surface). If speed remains constant, Should I use bigger wheel to enable the robot to climb easily? ...
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0answers
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Torque on a quarter-wave plate… Where is the force? Where is the moment arm?

If you shine circularly polarized light (carrying angular momentum) through a quarter-wave plate, the light will emerge as linearly polarized light (carrying no angular momentum) from the other side. ...
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0answers
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Transverse speed of hamster in wheel as function of theta

i need help with conceptual understanding of how this system works. A small animal is running in a wheel with radius R, (and 0 mass). When the animal is at an angle $\theta = \alpha $ measured from ...
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1answer
95 views

Torque required by a motor: using a counterweight to reduce?

I have a motor and gearbox that is rated for a certain amount of torque in newton meters. Its primary load $M_1$ is connected by a rigid rod (assumed massless) length $L_1$. So I reckon the (max) ...
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2answers
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Would a force not cause acceleration $a=\frac{F}{m}$ if part of it is used to cause rotation?

Let's say we have a massless rod of length $2\,\mathrm{m}$ that has a $1\, \mathrm{kg}$ ball at one end and another $1\,\mathrm{kg}$ ball at the other end.$$ \begin{array}{c} {\displaystyle{~\large{{\...
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1answer
60 views

Gyroscope physics

I'm not a physics student, but am attempting to better understand gyroscope physics. Also my first post here. So, I'm looking at this site, at the second diagram with F_1 and F_2, and reading the ...
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4answers
1k views

What is a moment?

As a 8th grader I am still a newbie at science and I have problems understanding the forces that I can not imagine and one of these "forces" is the moment. We are told that, $$\text{moment}= Nm$$ ...
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2answers
88 views

balancing a weight on a table without tipping over

I have a statics problem. Here is a model for a table: a circle of radius 1.5 ft a pole in the center a base in the shape of an X. I place a weight on the table on the edge. How much weight can ...
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1answer
75 views

Finding the state space representation of a dynamic model with the force and angle as control inputs vector

I am trying to design a controller to control the angle of the force on my mobile rigid body. I some questions: I am not sure how to write the state space representation with the force, $F$ and angle,...
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2answers
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How to measure change in degrees per second, given force applied at a certain angle? [closed]

Example: a rectangular spaceship weights 10.000kg, and has a lenght of 20 meters. A force of 1.000 newtons is applied at a 90° angle and 9 meters away from center of mass. What will be the change in ...
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1answer
79 views

Which equation should I use to find torque?

I'm designing a ball launcher that uses 2 wheels to accelerate a ball: Each wheel is driven by its own motor. I selected a desired speed for the balls to be launched at, $v_{\text{ball}}$, and so I ...
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3answers
229 views

Torque - Why does a block topple and net torque when net force is non-zero?

Suppose there's an inclined plane with friction $\mu$ (possibly $\mu = 0$), and there's a rigid cuboid block on it. Now while it's physically intuitive to me that the block will topple over only when ...
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2answers
80 views

If the torque caused by a force is cancelled out, is the force cancelled out as well?

I calculated the value of $\theta$ to be $53^{\circ}$ for (ii) by using the principle of moments ($6\sin\theta r 2 = 2.4 r$ ) as the disc is in equilibrium. Nothing wrong so far. For (iii), I ...
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0answers
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Calculus of torque to move a small vehicle

I have a to choose two DC motors in order to carry a vehicle. I assume that the mass of the whole vehicle (all components included) is 1Kg, the surface is flat and made of wood, the wheel coupled to ...
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1answer
44 views

Unusual Door Mechanics At Play [closed]

We have a door in our Applied mathematics lecture venue, that seems to open and close itself randomly (at about a 1-2 min interval). The door is not electrical and there is nobody pushing it from ...
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1answer
31 views

Adding momentum to pulling force

A winch is pulling a 90kg object in any direction but it is limited in potential speed by its torque. Would a burst of momentum by perhaps a coiled spring or jet propulsion pushing the object towards ...
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1answer
208 views

Pivoted Rod Problem [closed]

Hi this question popped up on AP Physics C practice test, and I keep on getting T = mg/2 through equilibrium. I got the torque from gravity is mgsinthetaR/2 and the torque from the Wire is TsinthetaR, ...
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1answer
508 views

Static equilibrium- when do you use forces and when do you use torques?

I'm working on an answered physics question in the book but I'm having trouble understanding why the problem could be solved by setting net torque equal to 0 and not net force. You are asked to find ...
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1answer
93 views

Formula for rotational work

I read online that rotational work is defined as $$W =\int \tau \mathrm{d} \vartheta$$ which is not exactly the same as $$W = \int \vec{F} \cdot \mathrm{d}\vec{r}$$ So i was wondering if it possible ...
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2answers
276 views

Torque/Rotation & Sliding with Slipping

A student holds one end of a thread, which is wrapped around a cylindrical spool, as shown above. The student then drops the spool from a height h above the floor, and the thread unwinds as it falls. ...
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2answers
103 views

Angular momentum paradox

I want to analyze the following system, where the mass of the axle is negligible and the Wheel is spinning. In particular I need to calculate the amount of torque about the point where the string ...
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1answer
129 views

Can the reference point in an inertial frame be accelerated when applying torque equation?

Torque about a point = rate of change of angular momentum about that point. Say we're in an inertial frame and see a body accelerating and rotating and another point(either a part of this body or an ...
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1answer
235 views

Angular acceleration in rigid bodies

This is a concept which is bothering me a lot. I'm sure there are other duplicates to this question but on seeing a few such duplicates, I haven't yet obtained an answer. My question is, for a rigid ...