# Questions tagged [torque]

This tag is for questions regarding to torque, which is a measure of the increase in angular momentum over time.

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### How to determine the frictional torque at engine idling condition? [closed]

What will be frictional torque at idling speed will it be lower or higher than the engine torque at idling speed?
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### Why does torque increase with radius or distance from the centre?

Why is it that making a perpendicular force farther away from the axis of rotation increases the rate of change of angular momentum (hence, torque)?
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### Equation to calculate the energy needed to turn an already rotating wheel on its axis of plane while forcefully stopping precession [closed]

Lets say wheel is rotating on Z axis clockwise. I am securing the wheel to the ground with two points (A and B) on the circumfrence of the wheel intersecting with the horizontal axis X. and wheel is ...
96 views

### Maximum Velocity of Car in Circular Motion Without Tipping?

We are tasked with finding the maximum velocity of a 4-wheeled vehicle undergoing circular motion without tipping (assuming that the force of gravity will act at the car's center of mass and the the ...
41 views

### Why is the output torque less than the input force of 20N applied from a wrench having length of 0.8m?

A wrench is of length 0.8m, or any number below 1.0m, I am exerting a force of 20 Newtons on the point A (one end of the wrench), on point B there is a bolt (on other end). If I calculate the Torque ...
1 vote
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### Calculate rotation from net torque and inertia matrix

I am trying to grasp the concepts of forces applied to a rigid body resulting in a net change of the rotation of the object. This is not a home assignment and I read some resources on both the web and ...
29 views

### Will the contact force value be affected by the change in the combined MOI of rod and mass?

A rod with a fixed pivot is rotated by torque T so that its free end pushes on different masses (see images A, B and C). Let's assume there is no force of gravity involved. Will the combined MOI of ...
1 vote
163 views

### Is Joule equivalent to Joule/radian? [duplicate]

The work a constant torque does when it moves a particle through an angel $\theta$ is given by $\tau \theta$. The work is measured in Joule, so the torque should be measured Joule/radian, but the ...
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### Equations for Torque Capacity and Bolt Clamping

I am doing research into how I can best approximate the torque capacity of several components bolted together in an assembly and specifically when a pattern of bolts is holding several parts together ...
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### Problem while calculing the bending torque of internal air pressure in a soft actuator

this is a question I cant resolve while looking a paper I needed for my undergraduate thesis. In this image (from Modeling of Soft Fiber-Reinforced Bending Actuators, Panagiotis Polygerinos et al.), ...
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### Can the brakes of a Semi-trailer truck overcome the torque of the engine? [closed]

On the average Semi-trailer truck, assuming an average load, can the engine overcome the brakes and continue spinning the wheels despite the operator applying the brakes fully? This would be assuming ...
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### Torque profile with fixed boundary condition

I am trying to find a simple treatment of elasticity theory of a scenario where I have a thin rod attached to a disc (radius $r_0$), and the disc is held fixed at its edge. Now I apply some torque to ...
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### Rotational Equilibrium With Forces acting on only two points

Imagine a rod that is held at angle to the vertical by some hook. The rod is in equilibrium. There would be three forces on this rod - Normal contact, Friction, and the weight of the rod. I struggle ...
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### Misconception About Torque Log cutting example

LOG CUTTING "Three friends go camping in the forest with their families. They start collecting wood to make a fire. They find a large, branchless log in the forest. One end of the log is very ...
1 vote
51 views

### Sign of distance/arm when finding moment/torque

I know that $M=Fd$, but when I have a negative moment, does the sign of the moment matter when I'm calculating for distance? If yes, then what would it mean when distance is negative?
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### What causes an arrow to rotate? [duplicate]

My intuition: In a system without air resistance, I would expect an arrow shot at an angle with its head pointing upwards to follow a ballistic trajectory without rotating around the horizon - because ...
29 views

### Calculate weight distribution on 2D plane

I am trying to figure out how I can have a formula for the weight distribution on a square. But let me just describe what I am doing, We have the classical horizontal beam support problem And I we can ...
265 views

### What exerts torque on a pulsar? [duplicate]

I'm modeling a pulsar as a rotating compact body with frequency $\omega(t)$, and magnetic dipole moment misaligned from the axis of rotation by angle $\chi$. It's straightforward to calculate the ...
50 views

### Is Torque always defined about the axis of rotation?

My professor told me torque can be calculated about any point in space, but would such a torque ever make sense even if the particle is rotating about some other axis, on which the point does not lie?
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### Choice of axis in analysis of gyroscopic precession

In many demonstrations of analysis of gyroscopic precession, the analysis goes on by choosing two axes, one about which angular momentum is calculated, another about which torque of gravity is ...
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Consider a free body, not hinged about any point. If a force is applied to one end of the body, the body has a net nonzero torque about many points in space. About which will it rotate? Am I wrong in ...
156 views

### What does the geometric product between displacement (or maybe position) and force vectors mean?

So work is measured in joules, which is newton * meter, and it is calculated by taking a scalar product between displacement and force vectors. And torque is very similar, it is newton * meter too, ...
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### How to calculate total moment around $z$-axis when the armlengths are not the same for all motors on a hexacopter?

I wonder how I can calculate the total moment around $z$-axis at a given rotational velocity for the motors on a hexacopter. My intuition tells me that motors that are more distant to center of mass ...
1 vote
136 views

### Axis of rotation of a spool unwinding and falling under gravity

There is a problem that asks for forces that apply torque around the axis of rotation on a spool of string that falls and unwinds under gravity. The spool falls straight down with a vertical string. ...
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### Interpret momentum applied on a rod when holding it from one end

Yesterday I started wondering exactly how much more effort it takes holding a rod from one of it's edged instead of from it's centre. Picture a rod, held by your hand from under it's centre. The force ...
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### Why does force decrease with increase in velocity in case power was constant?

Suppose an internal combustion engine burns the same amount of fuel every cycle (regardless of engine or car speed ) that means it creates the same pressure every cycle and the force on the piston due ...
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### How does a magnetic field do work on rotating a current loop?

Lorentz force tells us that the force on a charged particle by a magnetic field is always perpendicular to its velocity. So its a pretty well known fact that a magnetic field doesn't do work. But we ...
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### Why does the period of precession of a gyroscope have to be way larger than it's spin period so that it's motion can be modelled?

Mathematically, torque induced gyroscopic precession may be modelled with the following equation:  {\displaystyle T_{\mathrm {p} }={\frac {4\pi ^{2}I_{\mathrm {s} }}{\ mgrT_{\mathrm {s} }}}={\frac {...
1 vote
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### How can you determine if a bar will tilt with 2 points of rotation?

Say we have the typical press machine in the gym to exercise your chest, it is usually helped with 2 points of contact and weights on the sides of the points of contact: (Sorry for the quality) How ...
220 views

### Difference between moment and couple

What is the exact difference between a moment and a couple? In some YouTube channels and books, they say the moment of a force produces a translational as well as rotational motion whereas the concept ...
1 vote
96 views

### When do we use dot product and when do we use cross product? [closed]

I actually dont understand that when do we use cross product and when to use dot product ……it is very difficult to remember that a torque is cross product and work done is dot product. please tell me ...
1 vote
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### How do I translate force in one point to another point in an object? [closed]

For a project I need to model a system where a body can pivot at one point, and is lifted up by a piston, to rotate the body around the point. I am having trouble finding the formulas and ways to ...
1 vote
105 views

### Torque on a current loop in a uniform magnetic field

I'm trying to prove the result the net torque on a current loop in a uniform magnetic field is $\vec{\tau}_{net}=\vec{\mu}\times \vec{B}$ where $\vec{\mu}=I\frac{1}{2}\oint(\vec{r}\times d\vec{r})$ ...
1 vote
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### Why don’t you fall when you lean on a bike while it turns?

Let’s say you’re on a bike and you turn left and also lean left with it. As we know fron experience you remain stable. How is this? There is obviously a torque caused by gravity at the center of mass ...
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### Why don't bike wheels behave like a gyroscope when you turn them?

Let's say we have a bike pointing forward in the $+z$ direction into the screen. It's moving in the $+z$ direction hence the wheels have angular momentum in the -x direction ,which is towards the left ...
61 views

### Why doesn't a resting bar always rotate when pushed upon?

I'm trying to clear up some of my understanding about torque. Imagine that we have a uniform, heavy, thin metal bar resting on a table with less than half of it hanging over the edge of the table. My ...
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### 2 rods connected at a pivot and attached to a spring

I have a question concerning this problem First I calculate F1 by taking the origin at F2 and imposing equilibrium for the torque thus getting $F_1 = \frac{a}{a+b} F$ and similarly for F2, then I ...
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### What is the most fundamental reason for introduction of force moment $\vec{M}=\vec{r}\times\vec{F}$? [duplicate]

Force moment is defined as $\vec{M}=\vec{r}\times\vec{F}$ when force is perpendicular to the lever arm. How do we know that it has to be this way? How do we know it is not $F\cdot r^2$ etc. ? My ...
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### Prove that the derivative of the relativistic angular momentum is the relativistic torque

In the book "relativity" by Vincenzo Barone, the relativistic angular momentum tensor is defined as: $L^{ij}= x^ip^j - x^jp^i$ (With the indexes $i,j$ going from 0 to 3) And the relativistic ...
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### Torque on a current loop in a magnetic field, could you please explain the derivation and concept?

Torque=mxB Consider a rectangle loop pqrs of sides l and b , where pq and RS are perpendicular to field , I is the current, B is field , imagine that this loop is placed between 2 magnets. Force ...
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### Why front wheel drive (FWD) is physically more stable than rear wheel drive (RWD)?

As generally known, FWD cars are more stable than RWD, but I don't know why and I couldn't find the reason. Can anyone explain me with physics concept? Additionally, I also want to know why driving ...
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### Is it possible to find the forces in this problem involving a block/beam/bar glued to the side of a wall?

This is a follow-up to a previous post of mine post. In that post, we concluded that a beam cannot be held in place by an application of normal forces in only one location if that location is off the ...
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### Horizontal bar with one fixed end held by support beams touching/"pinching" it at one location to keep it from falling — Unsolvable problem?

Suppose we have a horizontal rigid bar held in place by two reinforcement beams (one above the bar and one below the bar), both of which are attached to a wall, such that they "clamp" the ...
1 vote
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I am brand new here. I am a furniture maker and designing an Oval Pedestal Table for a client. I presented a design that I felt comfortable with, however my client has asked that I shrink the ...
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### Is the position vector an axial vector?

The displacement vector $\vec{r}_{ij} = \vec{r}_j - \vec{r}_i$ is of course a polar vector because it's completely independent of the choice of origin, but what about the position $\vec{r}$ which, by ...
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### Tipping a cylinder [closed]

A horizontal force is applied to the top of a cylinder, creating a torque on it trying to tip it over. Now I have wondered to what height should the cylinder be filled with water to render it most ...
1 vote
63 views

### How much should the disk/wheel spin for gyroscopic-precession to take place? Is there a threshold?

Suppose we have a spinning gyroscope whose disk is of mass $m$, spinning at angular velocity $\omega$, and attached to a rod of length $r$. The precession of the gyroscope around the $z$-axis will be ...
1 vote
45 views

Consider a horizontal long rod that is undergoing free fall. Consider the torque about an axis through the rod (perpendicular to the rod and to the direction of gravitational force), that is a little ...
Suppose we have a disk (of mass $M$) connected to a rod (of mass $m$) attached to a fixed pivot. (Note that initially I thought of the rod hanging off a rope, but I realized it would be better to ...