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

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moment of inertia help

Okay so lets say i have a lever with 2 objects on it, object one and object 2. object 1 has a mass of $m_1$ and is $r_1$ away from the fulcrum also object 2 has a mass of $m_2$ and is $r_2$ away from ...
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3answers
52 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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1answer
53 views

Transfer of angular momentum during oblique impact with(out) adhesion

I am solving a problem of 2 identical spherical particles colliding. The impact is oblique. I consider both normal and tangential contact forces. Tangential force is a combination of elastic force ...
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0answers
22 views

Calculating Oscillations of a small magnetic needle [on hold]

In a problem from a past physics competition paper, a wire, carrying a constant current i, forms a "V" shape (as shown below). Part four of the question states In order to measure the magnetic ...
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1answer
18 views

Forces Create Angular Acceleration And “Straight” Acceleration - But How Much Of Each?

Let me set up the following problem for a rectangle floating in space: We know its dimensions. We know its mass. There's a force pushing it for a known amount of time - we know the angle & ...
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2answers
30 views

What does torque depend upon?

What does torque depend upon? I know torque depends on force and moment arm, but does it depend on choice of origin? Because I think choice of origin determines its moment arm.
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2answers
290 views

Would this box on the floor rotate based on friction?

There is a floor that friction is proportional to its velocity (like $F=-kv$) and there is a box with its width as $l$ and its height as $h$. (you may assume that $l$ is longer than $h$). It is on the ...
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4answers
1k views

Why do rolling disc (coin) move in circular path?

We have a coin that is rolled such that it's tilted at an small angle $ \theta $. Question:: What turns around rolling disc so that it traces circular motion (spiral as it's speed decreses)? ...
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1answer
21 views

How is angular momentum conserved when torque is zero?

According to law of conservation of momentum , angular momentum of a particle is conserved when its torque is zero . Please make it easier for me to visualise this condition .
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1answer
53 views

How is Magnetic force on a current carrying conductor $Blb$

I was reading an answer about torque acting on a rectangular current carrying loop kept in a uniform magnitude field B. Force acting on each sides is $F_1$, $F_2$, $F_3$, $F_4$. It's written here : ...
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2answers
49 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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3answers
23 views

Humerus's Downward Force (Joints and Torque)

Why does the humerus, the elbow joint, exert a downward force in the following setup. I understand that the bicep must be involved in a force pair, but I identified the counterpart to the bicep's ...
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1answer
21 views

Torque in a 2-segment robot leg

I have a (hypothetical) robot with two legs, each with 2 segments, with a joint at the body of the robot and in the 'knee' of each leg, as in this (poorly-drawn) diagram: (Sorry about the quality and ...
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1answer
35 views

How does the weight of the pendulum's bob cause a torque?

I know that a force will cause a torque if the force has a perpendicular component to the distance from the pivot point. However, in the figure above, I can't seem to visualize how the weight of ...
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1answer
155 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
25 views

How to visualise the direction of torque?

Torque is analog of force in rotational motion and it has one of two directions I.e clockwise and counterclockwise . How I can visualise these directions . For example r and F are on same plane(x and ...
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3answers
84 views

Distinction between torque and force

Distinction between Torque and Force. Consider a case when a cylinder is rolling down a rough inclined plane. While analysing its motion, we consider the force applied by the friction and the ...
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2answers
2k views

Which force makes a wheel roll down the hill? What causes friction?

A wheel rolling down a hill has two axis of rotation. One is where the center or mass is and the other is the point of contact with the surface which acts as a fulcrum. I was trying to understand ...
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2answers
177 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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2answers
1k views

Why do people with bigger hands/wrists have bigger torque advantages in arm wrestling?

I have arm wrestled people with less strength than me who win simply because they have thicker wrists, or larger hands. It has nary to do with having better technique either, because their wrist size ...
2
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1answer
344 views

Line of action force

The task is to reduce the two forces into a single net force and then find the equation of its line of action. I chose to find the net force and momentum with respect to the origin. The magnitude of ...
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0answers
33 views

Maximum friction force for a wheel to be able to roll

The wheel with mass $M$ and radius $R$ below is free in space (it is not on the ground). A torque $\tau$ is applied to it through an engine. A horizontal force $F = \frac{\tau}{R}$ is also applied to ...
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0answers
21 views

How does ground interact with a box rotating around its corner?

I have some questions about how forces $F$, friction force $F_{friction}$, and normal $N$ interact in order to the box below to turn (clockwise) about the red corner, without sliding. The force $F$ is ...
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1answer
39 views

Is a motor HP torque directly proportional to the increasing HP among identical motors?

Say you have three motors: Motor 1 = .10 HP with x torque, performing task A Motor 2 = 1 HP with y torque, performing task A Motor 3 = 10 HP with z torque, performing task A If the motors are the ...
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2answers
166 views

What causes a tall box to tip over on an inclined plane?

I'm wondering what makes a tall box rotate about its edge (the red point on the figure below) on a inclined plane (with or without slipping), when subjected to forces of gravity and friction only: ...
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6answers
2k views

Why does the weighing balance restore when tilted and released

I'm talking about a Weighing Balance shown in the figure: Press & Hold on onside of the horizontal beam and then release it. It makes some oscillations and comes back to equilibrium like shown ...
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3answers
304 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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3answers
68 views

What happens inside a body when it rotates?

I'm studying rigid body dynamics lately. I came across the definition of torque, and though I've found a lot of explanations as to why there is an r there (the moment), all of them are mathematical ...
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0answers
26 views

What is the linear and rotational motions generated by a force not on the CG?

Given a force that is applied to a free body, not directly towards, or away from the centre of gravity, how would you calculate the amount of linear and rotational velocities generated, as the farther ...
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1answer
391 views

Finding the mass of bed/Patient [closed]

One of my friends has a problem and we don't know how to get this done, We want to to know the mass of a patient who is laying on a bed. One scales was put under the foot of a bed and weighed 232kg ...
2
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2answers
58 views

Torque, and the Law of the Lever

How fundamental is the Law of the Lever? It seems that we simply define torque as being $r \times F$, if that's the case, then torque isn't a derived quantity, is it? Something like the Law of the ...
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1answer
41 views

Would equations for a spinning top be an (x,y,z) vector [duplicate]

I am following the equations on this page, and for torque it is $mgr\sin\theta$, but I am curious about $r$. I am working on a game and I want to correctly model the top, and am curious if $r$ should ...
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2answers
38 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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1answer
87 views

Calculating Resultant Force and Torque

I'm working on a sandbox game that allows the player to build a spacecraft and attach thrusters in arbitrary locations on the hull of the spacecraft. The game is set completely in 2D. (I'm a ...
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0answers
15 views

Why do we consider the application of force as well as bending moment in finding the moments of a beam?

In the standard techniques of beam related problems, solving for moment at any cross section includes counting the torque due to shear force as well as some extra moment, which according to me ...
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2answers
84 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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1answer
2k views

Is angular momentum always conserved in the absence of an external torque?

Consider either the angular momentum of the earth around the sun or equivalently swinging a ball horizontally on a string. I know that with respect to the point of rotation of the swinging ball, ...
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1answer
41 views

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

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 ...
2
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3answers
69 views

torque on a body without any supporting point [duplicate]

Suppose there is a rigid body in space and one single force is acting on it and the force does not pass through the center of mass. I would like to ask why the torque on a body is always the force ...
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5answers
1k views

comparing torque and 0-60 speed in cars

Im looking a two cars, both are the same model but ones got a 2.0L turbo petrol engine and ones got a 3.0L turbo diesel engine. These are the full specs 2.0L Petrol 3.0L Diesel what im ...
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2answers
64 views

Free vs bound vectors and torque

When considering basic Newtonian mechanics, we can treat vector as free and move their point of application at will. This is consistent with the affine nature of Euclidean space. However, when ...
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2answers
104 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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2answers
55 views

Applying a force on a rigid body which is used to create torque

In the above picture, I have a rigid body, in turquoise, which is connected to a point, the red circle. The dotted lines are used to divide objects or lengths, they are not part of the rigid body. ...
2
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1answer
56 views

Considering the theory of special relativity: Is torque still a vector?

Considering the theory of special relativity: Is torque still a vector? In classical mechanics it is easy: You have 3 axes and thus 3 planes. Every plane has its own torque so torque has 3 ...
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1answer
57 views

Torque definition and right hand rule not arbitrary

I have read the following: http://www.feynmanlectures.caltech.edu/I_20.html#Ch20-S1 The formula for $\tau_{xy}$ is derived in this chapter: http://www.feynmanlectures.caltech.edu/I_18.html#Ch18-S2. ...
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0answers
40 views

Torque of person on bridge [closed]

Consider a 10 meter bridge that weighs 500 N supported at both ends. A person who weighs 750 N is standing 2 m from the end of the bridge. What are the forces $F_a$, $F_b$ holding the bridgeup at ...
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1answer
90 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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1answer
93 views

Torque due to Gravity

I have learned that a torque on an object due to the gravity can be calculated as if the gravity acts on the center of mass of the object when the object is near the surface of the earth. Now I want ...
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2answers
68 views

What point of application of force ensures more acceleration in a rod?

Suppose there is one rod and a force F is applied in two cases: Case 1: exactly at the middle on center of mass Case 2: at one end of rod In which case would the center of mass of rod be accelerated ...
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1answer
56 views

How can a generalised force be dependent on an angle i.e. not a vector?

I'm currently working through an example question in Patrick Hamill's 'A Student's Guide to Hamiltonians and Lagrangians'. The question I'm having conceptual difficulty with is: A particle is ...