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

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Torque of a winch with pulleys [closed]

I'm working on a project that involves using a remote-controlled electric winch to raise and lower my bicycle using a pulley system. The problem is that I don't know how much torque will be required ...
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1answer
333 views

Torque on a Box

I think I'm missing something with torques. I seem to have gotten myself confused. I have a box that's centered at ( 0 , 0 , 0 ) with length ( $x$ dimension ) = 1 , width ( $y$ dimension ) = 0.25, ...
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62 views

Two impulses on body

Say I have a physics simulation with a single body with three degrees of freedom (two axis and rotation). I have two impulses of equal magnitude in opposite directions. When applying these impulses in ...
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461 views

Torque, lever and mass

The Force used in a catapult is exerted near its axis. If we double the length of the arm of the catapult, but still use the same Force at the same point as before near the same axis, does the ...
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1answer
165 views

Truck driven from a small motor that can carry a heavy load, yet can travel fast. [closed]

I am building a truck from trash as materials. I have one small motor and a a few small gears, but no other engineered materials are allowed. The truck must carry a load for a distance of 3m. The ...
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2k views

Neglecting friction on a pulley?

So, this is how the problem looks: http://www.aplusphysics.com/courses/honors/dynamics/images/Atwood%20Problem.png Plus, the pulley is suspended on a cord at its center and hanging from the ceiling. ...
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2answers
119 views

How bicycle gear works?

Based on the concept of the moment of inertia, my book gives the following relationship between the size of gear and amount of torque supplied to the drive wheel: Because it [outermost gear] had ...
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1answer
1k views

Back motor effect of loaded generators?

The back motor effect (see Counter-electromotive force) is the counter torque which opposes the rotational motion of the coils in a generator when the generator is under load. The back motor effect ...
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230 views

Angular momentum paradox with 2 identical gears

Consider two identical gears touching each other. The system is friction less. One has a handle that you use to apply a torque on the entire system. If you turn the handle, there will be a non-zero ...
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149 views

Is torque still a vector in 2 Dimensions?

In 3D, torque is defined as $\vec{r} \times \vec{F}$ which is a vector, therefore having both a direction perpendicular to the plane of $\vec{F}$ and $\vec{r}$ and a magnitude of ...
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3k views

How much torque does it take to turn a doorknob? [closed]

How much torque does it take to turn a doorknob? I'm not looking for an exact answer, just a ballpark for someone who doesn't have a sense of everyday amounts of torque. Here's a very ordinary ...
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40 views

Why don't barbells tip over when a 45 is placed on one side?

A standard barbell is 45 pounds, as is the heaviest weight available in most gyms. When a weight is placed on the side of a barbell, some of the barbell is to the "outside" of the weight, like so, so ...
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30 views

Is it okay to use the same moment of inertia formula for both a door turning on hinge and a long thin rod rotating at its end?

My book says you can redistribute the mass elements of a object to simplify its moment of inertia formula. But squeezing a door into a rod would change its density. Does it matter?
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6k views

Confused on how to properly use right hand rule

I am having trouble using the right hand rule properly and often find myself putting my hand in awkward orientations. I know you point your hand in the direction of $r$ and then point your fingers in ...
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2answers
361 views

Mathematically determining the direction of torque?

I need to mathematically derive the direction of torque in a 2D plane(clockwise/anticlockwise), for a physics engine. I have torque calculated, but it is always positive, so rotation always is in the ...
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968 views

Is it reasonable for a heavy door to “open by itself” (ie from differences in air pressure) if it had already been slightly ajar?

If you consider a basically uniform massive door (say, 300 N) where there is some coefficient $\mu_{s,k}$ of static and kinetic friction between the thing on the inside of the door, and where the ...
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1answer
112 views

How to work out the gravitational potential energy of rotating rod

I know that the kinetic energy of a rotating rod is $$ KE_{rot}=\frac12I\omega^2 $$ where $I$ is the moment of inertia. But is there some way to calculate gravitational potential energy using just ...
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2answers
155 views

How do I write the units for this answer? [closed]

If the force (at 90∘ to the lever arm) applied is 15 N and it is applied at 2.0 m from the pivot point (point of rotation), what is the torque on the lever? Is it 30.0 N/m?
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409 views

Conservation of angular momentum

We were learning about angular momentum in class today, and although it sort of makes sense, it's much harder for me to think about than linear momentum. So from what I can tell: Angular momentum ...
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731 views

Equilibrium of Force Systems including Torque

please help me to solve this problem.. this is only the #3 on my homework and the only thing i didn't know here is how to calculate the tension T. please teach me how to solve the tension here ...
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2answers
341 views

Is my physics correct or torque correct?

I would like to put this into a differential equation. This is what I have. $$r \times F = I \ddot\theta + \mu \dot\theta + k \theta$$ What I need verified: $\text{Torque} = I\ddot\theta + \mu ...
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1answer
2k views

how to calculate minimum torque a DC motor needs to move the wheels

Im making a robot that must sense objects and pick them up. I need to order some motors, so i wanted to work out the torque needed just to push one wheel (as it may pivot, so one wheel will need to ...
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2answers
21 views

What determines whether a mobile will hang in stable or unstable equilibrium?

Asking for a friend trying to make a Calder-style hanging mobile: https://www.google.com/search?q=mobile+calder&tbm=isch I understand torque just well enough to get it to balance (theoretically). ...
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59 views

What exactly is a torque?

I know there are a number of questions concerning torque on this site but I still don't quite understand what it is. A video by veritasium on gyroscopic precession ...
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1answer
42 views

Torque and Angular Momentum

An ice skater is spinning in a circle with an angular velocity, $\omega$, and rotational inertia $I$. Let's say that the skater then pulls his arms directly inwards at a constant rate over a time of ...
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91 views

Who told us how to measure torque?

We all know that force and torque are physical quantities which we have defined according to our purpose of work. Now we are all aware that Newton's Second Law from his Laws of Motion states how to ...
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1answer
69 views

Doubt related to rotational motion (rolling down an inclined plane)

I have doubt regarding when an object ( sphere , ring , cylinder etc ) rolls down a FRICTIONLESS inclined plane. Let us suppose the angle of inclination of inclined plane is θ. Now the forces acting ...
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1answer
107 views

Torque Approximations Neglecting Friction

Disclaimer: I'm not asking for homework help. I don't understand how my calculations work out conceptually. If you can help me understand the connection between the concepts, I'd really appreciate it. ...
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1answer
33 views

What happens with an originial force if a part of it creates a torque?

Let's say I push with an angle of 45 degrees at an object with a force of 100 N. Since the angle is 45, we would have a torque $\tau = 100 * sin(135) * r = 71N*r$ Since the force was not ...
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1answer
124 views

Torque considered about different points in a system [duplicate]

If we consider the torque about point A, there is none, so there is no rotation about point A. If we consider torque about point B, there is a net torque which means that there is rotation about point ...
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3answers
312 views

Torque on a disc?

In the following diagram: Point(c) is a going into the page and attached to the disc, Point(c) applies a torque($\tau$) to the disc, and it starts to rotate due to that torque. And if point(c) was ...
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1answer
139 views

Rotational Equilibrium Problem [closed]

The question is as follows: One end of a uniform 4.0-m rod, whose weight is w, is supported by a cable that makes an angle of 37° with the horizontal. The other end of the bar rests against a wall ...
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1answer
43 views

Torque and rotational motion

What happens if the torque is perpendicular to the axis of rotation or torque is in the direction of rotation?
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219 views

Tipping over objects on a frictionless surface

Is there any way you can topple over a rod which is standing up on a frictionless surface?
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78 views

Rotational dynamics about a point or an axis?

In several books and sites, its written that torque is calculated about an axis and angular momentum is calculated about a point. In MIT's Angular momentum lecture pdf, Angular momentum has been ...
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2answers
1k views

Torque and Pulleys [closed]

I have the solution to the problem below, however I approached the question differently than my professor and I do not understand why my answer is different. Can someone help explain where I'm ...
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2answers
258 views

Definition of torque for a continuous body

I am working on basic physics definitions. Given a particle at position $r$ (in some coorinate reference system) upon which acts a force $F$, the $torque$ $\tau$ is defined by \begin{equation} ...
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3answers
191 views

Reconciling Units in Classical System Analogies: Why Does Torque Have Units of Energy?

In classical physics we often cast an analogy between translational and rotational systems Force < > Torque Energy < > Rotational Energy Momentum < > Angular Momentum and considering SI ...
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2answers
174 views

How to take in to account torques applied at different points

Suppose we have a rigid body with known moment of inertia through some axis ($J$) and that there are multiple torques being applied in different points in that body. I know that for a rigid body, the ...
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1answer
364 views

Can a ball stay still while laying on a inclined plane?

Suppose there is a ball on an inclined plane. So, there are three forces acting on it: normal force from the plane, gravity (which can be decomposed in the component of gravity perpendicular to the ...
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1answer
65 views

At the instant of release of an object from rest. Is the only force that can act its weight? [closed]

Q3 from a mechanics exam past paper: I can do parts i) and ii) but for iii) in finding the angular acceleration, i used $C=I\alpha$, where $C$ is the applied couple or torque, $I$ is the moment of ...
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2answers
675 views

Work done by magnetic field on magnetic dipole

In the above slide, it reads that $W=\int\mu B sin(\theta)d\theta=\mu B cos(\theta)$. But, I thought that $\int\mu B sin(\theta)d\theta=-\mu B cos(\theta)$ by some calculus calculation. Can ...
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1answer
59 views

If the axis of rotation is fixed, is it ok to say clockwise torque?

I know that the direction of torque is along the axis of rotation, but would it be acceptable to say, for example considering a vertical thin rod in the x-y plane with a force acting on the bottom end ...
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164 views

Why can't I calculate center of mass via torque? Results off by a few percent

Why do I keep getting a slightly different result from the following two ways of determining the center of mass of a rigid, geometrically simple object? The object is a rectangular 5(x) by 7(y) ...
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1answer
258 views

Forces on a helical screw?

The common screws which we use, are right handed helices, the simplest parametric equations of which are:- $$x(s)=\cos(s),y(s)=\sin(s),z(s)=s$$, with $z$-axis as the axis of the helix. My question ...
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2answers
4k views

DC Motor Torque Constant

I am very new to DC motors and to stackexchange. Please correct me if anything I said does not make sense. For DC motors, the equation looks like this: $P = \tau\dot{\theta}$ where $P$ is power, ...
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1answer
280 views

Horsepower achieved with multiple motors

Scenario I'm planning to build an electric motor for fun (not for any practical purpose). I recently purchased a shapeoko CNC mill kit and intend to manufacture most of the parts housing, stator etc. ...
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3answers
416 views

How to imagine the following power and torque?

I can roughly feel a force of 10 newton only by considering the weight of 1 kilogram object. How to imagine the following measurements? Maximum horsepower 16 hp @ 9,500 RPM Maximum torque ...
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1answer
303 views

What causes a gyroscope to eventually rotate/fall over?

Hey so I've just learned about angular velocity and momentum and how torque changes it. Looking at a wheel spinning around an axis, with one end being held up by a rope, what causes the wheel to ...
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1answer
440 views

if a force is 1 newton metre, what is it at 2 meters?

If I have a force, say 24 kg/cm what would that equate to at 2cm? I would like to know the formulae for calculating this. For example. If a motor can hold an object of 24kg at 1cm from its pivot ...