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

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When will a cylinder topple? [on hold]

a cylinder of diameter 2R and mass M rests on two rough pegs (coefficient of static friction is u ), distance 2kR apart . an increasing torque is applied in clockwise direction. the cylinder will ...
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26 views

Force required to swing gate open/close

I need to know how to calculate the force required to swing the gate open / close. If it is moving straight, we can use f=ma, but how to calculate for swinging motion? When I open or close the gate, I ...
1
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2answers
30 views

Torque: The T-shaped stick problem

This is a problem that I have been unable to solve for some time. Imaging a T-shaped stick, as shown in below image, which do not deform in any appreciable way and has pivot point at the tail of the ...
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1answer
20 views

Why, here, the torque with respect to bob is zero?

here, as you see, is a diagram of a pendulum with moving pivot along x-y surface. This picture was obtained from a journal in which this equation was written: $$F_x l \cos\theta = F_y l \sin\theta ...
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22 views

Conservation of angular momentum in a system under torque

Let's say we have a particle $A$ like this which is located in the disk $c$. Consider that the particle itself is not moving, but in general it is constrained to the semicircle $d$, in that if it ...
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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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2answers
38 views

Why can't a force between two particles exert a torque?

Let's say I have two particles which exert a mysterious force between them. Say they lie on the x-axis. Newton's 3rd law tells us that the force on the two particles due to the other must be opposite ...
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2answers
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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2answers
29 views

Direction of torque due to magnetic moment

I have a problem with determining the direction of torque due to magnetic moment on a current loop. Since the torque is defined as $$ \tau = p_m \times B $$ so I guess the direction of the torque ...
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0answers
25 views

Parallel axis theorem non-uniform density [closed]

The parallel axis theorem says that if the moment of inertia of a body rotating about the body's centre of mass is $I_{cm}$, then the moment of inertia of the body rotating about an axis parallel to ...
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2answers
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 ...
3
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1answer
30 views

Mechanics principle

When two forces of equal magnitude, opposite in direction and parallel act on an object, the object will rotate without having translational speed. On the other hand, when three concurrent forces ...
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1answer
21 views

Four bar linkage moment transmission

The question is. I know the angular velocity of $d$ after applying dynamic mechanics and the constant angular velocity of $b$ of $2\pi\ \text{rad/s}$ and I know the input moment of the power source ...
1
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1answer
58 views

How do I handle elastic contacts in a simulation with friction [closed]

I'm trying to simulate a wheel as it hits the ground. Problem 1 Suppose a disc is dropped from a height. It has initial velocity of $-x,-y$ caused by throwing and gravity. It has no initial angular ...
0
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0answers
17 views

Weight placement of turning motorcycle and traction

In the motorcycle racing world it seems that there's advice that one should place their weight on the outer foot rest when turning at high speeds, from some forums I've been looking at it seems like ...
0
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0answers
14 views

Forces in material removal (cutting, grinding, sanding, etc.)

A. Suppose a circular saw is spinning at a certain angular speed. When it starts to cut into the material, removing chips of the material or abrading it, the speed drops. The drop in speed depends on ...
0
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0answers
45 views

What is the derivation of $r*F=Iα$? [duplicate]

Please give me the derivation of the formula r*F=Iα for extended body. where, F=applied force r=distance between point of rotation & point where force is applied I=moment of inertia of the body ...
0
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1answer
31 views

Is a rotor balanced at constant angular velocity?

I have an asymmetrical rotating part. It vibrates its housing and emits audible noise. I need to add weights to ensure smooth rotation. However, I am constrained in which regions I can add ...
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1answer
39 views

Force (torque) to break a bike handlebar? [closed]

Few weeks ago a neighbor manage to hit my bike with his car while the bike was parked next to a wall, check the picture. One side of the handlebar was at the wall and the door of his truck hit ...
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1answer
30 views

can a single force rotate an object. not a torque

Can a single force (not a torque) rotate an object? How can the bar below fall given the force $\mathbf F$?
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1answer
39 views

With radian as a unit, should action and angular momentum have the different units?

If one accepts radian as a fundamental unit, does it make sense that action and angular momentum have units differing in radian to the power of one? The same question applies for energy and torque. ...
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2answers
67 views

Angular momentum changes depending on orign

Consider the image below where we have two point masses $m_1$ and $m_2$ with different masses which are rotating around a fixed axis with angular velocity $\omega$. If the origin is placed on the axis ...
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0answers
11 views

Stick stands in the corner then starts to fall, when will it detach from the wall? [duplicate]

A thin homogeneous stick stands on the smooth(no friction) floor, leaning against a smooth wall,stands absolutely vertically. (Imagine a corner).Then it starts to fall(with zero initial velocity).What ...
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1answer
25 views

Torque as if magnetic force were concentred in mean point

From what I see in my textbook and several on line resources (such as this, p. 8-8), I am tempted to think that the magnetic force $I\boldsymbol{\ell}\times\mathbf{B}$ acting on a straight conducting ...
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1answer
47 views

Rotational equilibrium Paradox

A block of mass M and height h is moving on a rough surface of coifficent of friction 0.5 .The block is moving with a velocity v at some instant. if we balance the torque due to frictional force and ...
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1answer
21 views

Changing angular momentum with no forces to do torque

Suppose a particle of mass $m$ moves in a straight line at velocity $v$ some distance away from an axis, as shown here at times t1 and t2 (where the axis of rotation is located at the origin of the ...
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1answer
40 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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What kind of torques cause an object to precess?

In studying precession, my textbook (Taylor's Classical Mechanics) makes the assumption that a top spinning about its symmetric axis, but tipped at an angle $\theta$, will precess nicely so long as ...
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1answer
33 views

Angular acceleration of a car door [closed]

http://imgur.com/F3eAF9F Edit: i uploaded to the site but it came out really blurry so heres the imgur link I don't get the solution at all, where does the -ma r cos theta come from? (Sorry on my ...
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2answers
59 views

Couldn't high gear ratio replace need for high torque engines?

I've noticed that there is a correlation between displacement and torque, so trucks, SUVs etc. have large displacement engines to produce lots of torque to move heavy loads. Sports cars have lower ...
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0answers
20 views

How to calculate motor torque & rpm

I watched a DIY video recently about a brushless DC motor. How would one go about calculating the max torque & max rpm (under no-load & a given load conditions) of that motor based on the ...
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0answers
21 views

How can I calculate the torque of draw force which affect on spinning ball flying in the air?

I am studying the Magnus effect on a flying ball i have calculate the magnus force but i trying calculate the angular acceleration, because the angular velocity of the ball is not constant. I have ...
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0answers
23 views

What point is the torque on a loop in a magnetic field taken about?

I know that the torque on a loop kept in uniform magnetic field is given by $$\vec{\tau}=\vec{M}\times\vec{B}$$ where $\vec{M}$ is magnetic moment. Now, can I take this torque about any point in ...
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1answer
45 views

What is a moment/torque?

What is a moment/torque? i know the formulas m = fxd (Nm), I know how it works, what is does etc. But think of it fundamentally, how is it possible, that a force becomes greater when the arm of an ...
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1answer
225 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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2answers
24 views

Torsion and twist in solid cylindrical beam

Well given a beam (as shown), a solid cylinder with radius R. A Torque $T$ applied to it, I need to solve the angle of twist ($\theta$) at the position where the torque is applied ($z$). The basic ...
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19 views

What is the general proof that the torque acting on an irregular current carrying loop in an uniform magnetic field is only dependent on area?

How do you prove that the torque acting on an irregular current carrying loop in an uniform magnetic field in the plane of loop = $I \vec{A} \times \vec{B}$ Where, $ \vec{A}$ = Area vector of the ...
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0answers
14 views

Total torque from direction cosines

I'm trying to determine an expression for the total torque on a rigid cylindrically-symmetric body subject to a rotational potential $\phi$. Let the orientation of the body be given by a unit vector ...
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2answers
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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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1answer
25 views

Why does a ball rotate sometimes when you throw it?

My guess is that when you throw a ball, which is held by your hand, using you arm, the radius of the circular path being constant, the outermost part of the ball has a bigger radius than the innermost ...
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1answer
28 views

What are some characteristics of r as in $\tau = mr^2\alpha$?

Can r just be the distance from an object center of mass to the axis of rotation? If not, it will be very hard to calculate r for things that are not particles, which doesn't exist in real life. ...
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19 views

what is significance of direction of vector product(torque & angular momentum)?how can one use them practically? [duplicate]

since i came across vector product or cross product i have one doubt that is what direction of torque shows.the direction of product is along axis of rotation(+ve or -ve).is there is any practical use ...
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2answers
92 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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0answers
28 views

Electric skateboard speed calculations [closed]

I have a slight issue figuring out how the mass of person (≈110kg) will affect the theoretical top speed achieved. Below are the details: (1) Motor kv : 270 kV (2) Batteries: 19.8V Motor Speed: ...
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1answer
46 views

Finding the coefficient of friciton [closed]

I'm asked to find the coefficient of friction before the bar starts sliding. Here is my solution -> ∑M = 0 -mg * 1.4863 + 1.8159*T = 0 (T*1.8159) i found by using a cross product ( -2.9726i+ ...
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1answer
90 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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25 views

How rotational force calculation depends on the distance between the point of force application and the axis of rotation?

I don't understand how the perpendicular distance between the point of force and the axis of rotation gets involved in the calculation of the rotational effect of that force.Is it about rotational ...
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1answer
27 views

Finding the friction before slipping [closed]

There is a string that is attached to a bar as shown below in the picture. What is the coefficient friction between the bar and floor before bar starts slipping. I have chosen a pivot point about ...
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2answers
57 views

Equilibrium equations

You have one horizontal beam. Its left point is attached to a free pivot at the vertical wall. Its right point is suspended by a rope from the ceiling. Nothing is moved. So $\sum F=0$ and $\sum M=0$. ...
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1answer
44 views

A leaf floating on the surface of water (in $x$-$y$ plane) curl along positive $z$ axis [closed]

A leaf floating on the surface of water (in x-y plane) show that for a very small circular leaf ($\nabla \times \overrightarrow v $) is equal to twice the angular velocity of rotation of the leaf, ...