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

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509 views

Can anyone solve this simple static equilibrium problem? [closed]

A bridge is 50m long, has a mass of 20,000kg, and rests on two pivots, A and B. The distance between A and the left side of the bridge is 10m. The distance between B and the right side of the bridge ...
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3answers
28 views

Converting moment of inertia (kg per square m) to torque or moment of force (in/lb or n/m) [closed]

My problem is that I have an dc starter generater and they say that to test it I must have a flywheel that can provide the starting inertia of .522 kg per square meter. What I need to know what will ...
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1answer
29 views

What is the intuition behind the direction of torque? [duplicate]

I've seen the other posts on this question, but unfortunately I'm still having difficulty understanding the meaning of the direction of the torque vector. It makes intuitive sense that the magnitude ...
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26 views

What are torque parameters?

Torque is just the turning force on an object, i.e the force multiplied by the perpendicular distance from the force to the pivot. But when torque parameters are mentioned in mechanical engineering ...
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26 views

Wikipedia's derivation of torque related to angular acceleration [duplicate]

Wikipedia derivation of the relationship between a torque and an angular acceleration is given here. Could someone help me to see how the following: $$\vec{\tau} = \left(-\sum^n_{i=1}m_i [\Delta ...
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17 views

Is it possible to impart a moment with soundwaves?

How can one adjust the properties of a sound wave to use it to spin an arbitrary object of shape S in a medium comprised of the same material. My intuition tells me that it would be much more ...
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54 views

Calculating the rate at which a car turns

This is going to be difficult to describe, as I have no real concept of this sort of physics, so please bear with me. If this is too much or beyond the scope of this website, I apologize. I am making ...
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40 views

Coordinate System vs. Angular Properties vs. Centroid

Please help me check my understanding related to the rotational motion of a 3D rigid body after reading some Physics textbooks and googling for some more materials (e.g., Wikipedia's Torque, ...
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2answers
96 views

Why does moment of force depend on the perpendicular distance?

Couyld anyone explain how the lecturer concluded that $$(\underline{r_2} - \underline{r_1}) \times \underline{H} = \underline{p} \times \underline{H}$$
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16 views

Can we always apply a pure torque at arbitrary positions on an object in practice?

I want to apply a pure torque to an object, say a square box on the ground. And I also require that the torque is generated on the corner of the square, not the center of mass. Is there any way for me ...
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1answer
46 views

Thrust to Weight ratio in Space with an off set CoM

With regards to this thread, Thrust center in space My question is, if the thrust to weight ratio was increased so that it was much higher than the weighted mass of the sphere (ship), would the ...
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34 views

Rolling resistance

Today, my physics teacher asked the following question (and gave it as homework): How can a moving body deaccelerate both in means of center of mass and rotationally? I quickly answered that ...
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61 views

Angular velocity in fluids (Air resistance)

Few days ago I started making physics engine on directx. As it obvious I have encountered one problem. I can't find formula of air resistance for angular velocity. I only able to find drag force, but ...
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1answer
90 views

Moment around a point in a frame

Note: Both diagrams are 2d(they might look 3d because I drew them manually.) I have a prismatic frame that looks like this: I made a section on the half of the first pillar(the red line represents the ...
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33 views

Gyrocompas equation

Ok, need a little help for part (b) of the following problem. I set my axis similar to figure 113 and have expressed both $\omega$ and $\Omega$ in terms of the new coordinates. I have been told to ...
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0answers
100 views

Correct way to calculate torque produced by axle

For my electrical engineering course, we had to build a simple DC motor that can lift a coin. I have tested the motor, and here are the results: rotational speed (no load): 3630 RPM (380 rad/sec) ...
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129 views

Torque of Air Resistance on Ellipsoid

Imagine an non-rotating arbitrary free, rigid ellipsoid with in some arbitrary direction with velocity $\vec v$. Assume linear drag ($\vec F=KA\vec v$ for some constant K, where A is the cross section ...
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1answer
698 views

Force acting on a simple rigid body in space

so this is the question that's been bothering me: Say you have a simple rigid body in space that is at rest or travelling with only translational motion at a constant speed. Say that the body is ...
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3answers
287 views

Calculating the torque at a point when a motor is stopped?

So, I'm trying to solve for the torque $\tau_A$ of a motor. I have attached a strong stick to the motor, like so: I apply a force $F$ on the stick which stops the motor. The distance from the ...
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0answers
142 views

What happens if torque = 0?

I am trying to understand torque on a current loop which is placed in a uniform $\vec{B}$-field. (http://i.stack.imgur.com/oNO8a.jpg) It says that $\vec{F}_2$ and $\vec{F}_4$ have the same ...
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0answers
126 views

Calculating rotor torque out of mass center

Suppose I have an engine with propeller. I know there is aerodynamic force pushing the propeller opposite direction the engine is turning it. One component of this force is creating lift, but second ...
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1answer
464 views

Calculating torque with gears and wheel-axles

For my homework in engineering, I was given a question like this: There is an axle attached to a gear, which is meshed with another gear, which has an axle attached to it. I am given the diameter of ...
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201 views

Dose the gravitational force produces precession in the spinning top?

I'm new at classical mechanics but the text book says there is the torque in the spinning top which generated only by gravitation. It is hard to explain the situation, I've add the link. ...
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1answer
76 views

Pendulum system: how is derived the output as Energy?

Good day to everyone, I want to understand in which way the "Energy equation" is been implemented to this pendulum system. $x_1(t)$: The angular position of the mass $x_2(t)$: The angular velocity ...
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1answer
279 views

How can the torque a bicycle experiences be calculated based on the center of gravity, weight and a force?

The position center of gravity of a bicycle and its rider is known, and the distance from it to the point of contact of the front wheel with the ground, in terms of horizontal and vertical distance (x ...
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348 views

How do you determine the torque caused by the mass of a lever?

Suppose we have two objects sitting on two side of a lever, and the lever also has a mass, and those objects have masses. Then how we can balance $\sum τ$? This is what I have done: ...
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2answers
380 views

Finding work done by rotational force?

A disk with a rotational inertia of 5.0 kg·m2 and a radius of 0.25 m rotates on a fixed axis perpendicular to the disk and through its center. A force of 2.0 N is applied tangentially to the ...
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3answers
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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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2answers
60 views

Torque for rotation

The force for revolution of earth is provided by the gravitational force of attraction between earth and the sun. What provides the force(torque) for the rotation of earth?
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1answer
61 views

does the current's direction on a loop with a magnetic field affect the torque?

I have a question in my book The question is very easy, but then my solutions manual gave me unexpected answers I don't get how in d) they conclude the vectors go in the opposite direction, but ...
-1
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1answer
478 views

Calculation of torque for motor used in 4 wheel robot [duplicate]

Possible Duplicate: Torque Required For a Motor to Move an Object on Wheels? I want to build a 4 wheel robot. the maximum weight of the robot is approximately 100 kg. and the radius of my ...
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0answers
24 views

How do I know which force to use in moments calculation?

I'm working on some Statics problem, with the method of joints, etc and for all of them, we use sum of moments = 0. However, I'm very confused about which forces I should use to find the sum of ...
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53 views

maths question on levers [closed]

Someone holds a 2kg weight in their hand at a distance of 35cm from the elbow (fulcrum) and the downward force (load) due to the weight is 20 Newtons. Calculate the effort in Newtons that the ...
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1answer
218 views

Proof for torque=force*perpendicular distance to line of action of force [closed]

I want to derive from first principles the proof for magnitude of torque about a point O = perpendicular distance from O to the line of action of the force * magnitude of the force. I want to derive ...