# Questions tagged [torque]

This tag is for questions regarding to Torque which is a measure of the force that can cause an object to rotate about an axis.

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### Conservation of linear momentum in a rotating moon

Imagine a car at the surface of a moon that accelerates forward. As the car pushes on the ground to move, the moon starts to rotate in the opposite direction. However, at any given instant the car has ...
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1 vote
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### Is torque possible without any pivot point?

In the picture, AB is a rod. The resultant of force P=10N and Q=5N works at point C which is P+Q. When I apply both forces simultaneously, the rod will rotate and accelerate. 5N from both end will ...
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### How to calculate force on actuator mechanism with acute angle

Trying to confirm the exact load needed for some actuation based on mechanism geometry that has already been fixed. Is there anyone who can help with this? I have a section through that shows the ...
1 vote
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### How to draw vectors?

The images show rotational motion.Here, $r$ is the position of the particle and $F$ is the force applied on it. Now, if I draw vectors $F_x$ and $F_y$ according to fig.2, I understand why it moves in ...
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### Physics of turning a water value (or rod) with lever attached to center

If a bar was attached to a water valve at its center, at 90 degrees, and an the end of this rod is where the effort was, which length do I use for the resistance arm? is it the distance from where it ...
1 vote
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### Moment of inertia of irregular object

How could you use a torsional pendulum to determine the rotational inertia of any object that could be mounted on the Rotary Motion Sensor?` Note: The Vernier Rotary Motion Sensor is a bidirectional ...
1 vote
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### How does torque frequency affect a wing's movement? [closed]

Preface I'm playing with a python based simulation in which I solve the ODE $I\ddot\phi=\tau_{motor}-\tau_{drag}$. This ODE represents Newton's 2nd law (in terms of torques) of a wing that is attached ...
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### Does the earth’s rotational angular velocity change?

This is what is written in The Feynman Lectures on Physics, Vol. 1 (ch.5) We now believe that, for various reasons, some days are longer than others, some days are shorter, and on the average the ...
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### Rigid body doing rotation [duplicate]

Is it possible that a rigid body is rotating but net torque about any point in the body is $0$? The reason behind asking this is if we apply two unequal like parallel forces at two ends of a uniform ...
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### Role of static friction in rolling

I am confused as to how does static friction (analytically) causes rolling motion. As far as i understand For causing a rigid body to rotate about its centre of mass a torque must displace angularly, ...
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### Torque and lever in a circle [closed]

Calculate the force (F) required for a person in a wheelchair to get onto the pavement with height h = $10$ cm. The total weight of the person and the wheelchair is m = $70$ kg and the radius of the ...
1 vote
80 views

### Movement of a rod submitted to a shifted torque

Suppose I have a rod of mass m initially at rest, for which a torque (F1, F2) is applied at the right side during a brief time $\Delta t$, as in the schema below. The rod is not fixed to anything and ...
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1 vote
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### Why are the directions of torques different with 2 people on each end of the seesaw?

In this picture, the book says the father has a positive(+) torque with direction coming outside the paper, and the daughter has a negative(-) torque with direction ggoing inside the paper. I knew ...
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### Given two forces acting on two parts of an object, can we find the location of the resultant force in this problem?

Suppose we have two objects $A$ and $B$ that are attached to each other. Suppose further there is a force $\vec{F}_{A}$ acting vertically on $A$ at $\vec{r}_{A}$ and there is a force $\vec{F}_{B}$ ...
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### Pseudo torque for angular acceleration

Suppose $F_{net}$ on a body is 0 (still it has torque). i.e. it is performing pure rotational motion. Now I want to consider torque about any point that is not center of mass. Should I include ...
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### Torque equilibrium of a cylinder

In the process of deriving the stress tensor of a cube which is shown in the picture below, it is concluded from the torque equilibrium equation that $\sigma_{ij}$ is equal to $\sigma_{ji}$. I am ...
1 vote
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### Definition of hydrodynamic force and torque

I am currently reading about the added mass effect. In the book I'm reading (Added Mass of Ship Structure by Alexandr I. Korantkin), the hydrodynamic force and torque acting on a body experiencing a ...
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### How does a particle have torque and angular momentum?

I'm aware similar questions have been asked, but I didn't understand the answers. Can a particle experience torque? What about angular velocity and/or acceleration? Assuming a particle is a body ...
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### inconsistency regarding axis of rotation in equilibrium analysis [duplicate]

If a system has no rotation, we should be able to choose any axis of rotation to do the torque equilibrium analysis. However, I found that in an non inertial system, different axis of rotation gives ...
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1 vote
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### Maximum acceleration without tipping over - torque balance analysis on an non inertial reference system

edit: This is not a homework question, but a question about whether choosing a different rotation axis can affect the torque balance analysis. I am just using the following example to illustrate ...
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1 vote
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### A question involving Torque

I have a few questions which have all seemingly originated from the following thought: Question 1 It is known that torque is given by τ=r × F. If we use the formulae F=mdv/dt and v=ω × r, we arrive at:...
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### Rotational equilibrium for an object

I have two silly queries: In case $1$,a rod $AB$ is attached to a string at point $C$. Here the weight is acting at the center of mass $O$. My question is: * Is it even possible to keep a rod hanging ...
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### Falling yoyo experiment

I was playing with a yoyo and a spring dynamometer and realized the tension during the fall is not constant but clearly has a small oscillatory component. This experimental result contradicts the ...
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### Necessary torque calculation for rotating a heavy object?

I'm trying to create something like the image below, where a motor will be connected to a gate/big piece of wood, which will be hinged so that the motor can rotate the gate. I know the weight (4lbs) ...
1 vote
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### Why does an extension cause my impact gun to have less torque?

I have an impact gun that I can mount an extension onto. It appears the longer the extension, the less torque the impact gun delivers ? Does this make any sense , or am I just imagining things
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### Contradiction between Force and Torque equations

A thin uniform rod of mass $M$ and length $L$ and cross-sectional area $A$, is free to rotate about a horizontal axis passing through one of its ends (see figure). What is the value of shear stress ...
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### Buoyancy and stability

I don't understand how does a rotating moment caused by the weight force form when a submerged object is tilted like this. I understand that the buoyancy force produce a moment about CG because of the ...
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### Why are inclined push ups easier?

I have been thinking and searching about this a lot and have still got all my doubts. My main hypothesis is that, since our body is actually rotating (and not moving) during push ups, torque must be ...
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### Sum of torques acting on car wheels

lets say we have a car parked on a slope and its in balance. There is a torque acting on the wheels pointing down, therefore there needs to be another force which causes a torque pointing up in order ...
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### How does an external non-conservative force act on a variable in the Hamiltonian formalism?

Consider a system subjected to an external non-conservative torque. The complete Hamiltonian is $$\mathcal{H}(q,p) = \mathcal{H}_{nat}(q,p) - \tau_{ext}(p) q \tag{1}$$ where $\mathcal{H}_{nat}(q,p)$ ...
1 vote
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### Why is the position of the centre of mass of the system changing in y direction if there is force only in the x direction?

I know that a tension force might act within the body, but it is an internal force and must not change the position of centre of mass of the system. The net force in the vertical(mg+normal) is always ...
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### What is conserved in the following motion? Kinetic energy or angular momentum ? only one answer

there is a body which is moving with a finite velocity and its velocity is perpendicular to its acceleration at any instant. Now I'm confused as no torque is applied angular momentum must be conserved ...
1 vote
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### Confusion about the Spinning Top

Consider the following symmetric spinning top with a fixed point on the horizontal surface. I have two questions concerning its motion: let $\underline{\Omega}$ denote the precession angular ...
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### Morin 2.16 - Balancing a semi-infinite stick

Problem 2.16 from Morin's Classical Mechanics: Given a semi-infinite stick (one that goes off to infinity in one direction), determine how its density should depend on position so that it has the ...
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### The utility of HorsePower vs Torque [closed]

All vehicles have only 1 gear Final-drives allow peak RPM (HP) at red line = 35 MPH Wheel-sizes are equal Tires have perfect traction (yet, no rolling resistance, etc) Goal: isolate all variables ...
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### Is it possible to change the speed at which a wheel is freely spinning by moving only its axle?

Suppose we have a wheel spinning on a perfectly lubricated axle. Is it possible to change its angular velocity about that axle, by moving only the axle? Due to the wheel's symmetry about the axle's ...
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### High school Momentum/Torque problem [closed]

This is embarrassing but I can't seem to solve this problem, even though I know how to resolve forces involved. The weight of the base is 868 N.
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### Can the value of friction force ever exceed value of applied force?

My teacher taught me that the value of friction force can never be greater than the applied force. But recently, when I was studying rotational motion, I got a dilemma… Suppose I made a stand (from ...
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### What specifically about the torque vector is perpendicular? Is the torque vector like this only so that it works smoothly with linear algebra?

What specifically about the torque vector is perpendicular? Is the torque vector like this only so that it works smoothly with linear algebra? The only explanation I get usually is "because it's ...
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### Which configuration is better for this electric motor?

I have a problem with this exercise, it's an electric motor. an electric motor works because of a magnet, and a wire with a current (i.e electrons moving in it). by turning on and off the current it's ...
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### Rotating a lever — small end has more force but less speed?

Suppose I have a massless lever with two masses at the ends and a fixed pivot as depicted below. Assume no gravity in this scenario. Further, let's say object $B$ is closer to the pivot, so $r<R$. ...
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### Work done By Internal Forces Inside a hinged Rotating Rod

Following the previous posted question , I got to know that Normal reaction is not doing any work as it does not displace any particles of the thin rod. But,I got another concept dilemma. There will ...
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### Work Done on a rotating thin rod by hinge Forces

So I was studying the concept of rotational energy through a video, and the guy presented a problem, It's like this: "Suppose a thin rod of mass M and length L/2 is hinged from one end. Then, it ...
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### Mechanics of an elevator bed/platform in a Tiny House

I'm building a Tiny House that will have a platform that moves about 1 meter up and down. Given that I have little to no experience using pulleys, cogwheels or any of the like, I'd like some feedback ...
1 vote
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### Traction Torque Effect On A Rotating Wheel [closed]

In the figure is shown an electric-car's wheel . If we made a dynamic force analysis to this wheel (which is considered to rotate in the anti-clockwise direction) ; We will find that a traction force ...
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### Serious confusion regarding central concept of torque

I have taken physics, statics, and dynamics, and I have no problem with applying the concept of torque to a problem. But, I just cannot grasp why a force a greater distance away from the axis of ...
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### How does one determine the direction of torque?

Torque is given by $$\vec{\tau}=\vec{r}\times\vec{F}$$ and it is a vector quantity. This means the torque has to be perpendicular to both the force and the radius. However, this doesn't seem to be the ...
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### Question regarding rotational motion [duplicate]

From here:Why does torque lead to rotation? I have got good understanding of rotational motion. But no one has answered the question: why both the ends of rods move in opposite direction? If the all ...