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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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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1 answer
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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 ...
3 votes
1 answer
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What causes this corkscrew-shaped object to rise up in a stream of water falling down?

A corkscrew-shaped object is floating in a tub of water. When water is poured into the tub from some height, the object starts rising up vertically in the stream of water. The water stream is falling ...
0 votes
3 answers
514 views

How is there moment for a group of forces which its resultant equals zero?

I am a beginner in mechanics, and when I was introduced to moments there was a theorem that says "if a set of forces acting on a rigid body has a resultant, then the algebraic sum of these forces ...
2 votes
1 answer
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Newton's 3rd Law Coil in Magnetic Field

When a current-carrying rectangular loop is placed in a magnetic field, the forces acting on either side of the loop which is perpendicular to the field provides a torque which rotates the loop. ...
3 votes
2 answers
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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 ...
-3 votes
0 answers
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Why is it easier to open a door from the far corner (explain without using the concept of torque or energy)? [closed]

I want to understand why is it easier to open a door from the far corner using only linear kinematics and dynamics in your explanation (without using the concept of torque or energy) or in other words,...
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0 answers
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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) ...
3 votes
3 answers
1k views

How is it possible to calculate the moment of inertia?

I would like to calculate the angular acceleration of an object on which a force $F$ is applied at point $P$. The scene is 2D, and the complex object consists of many axis-aligned rectangles. I ...
2 votes
2 answers
420 views

Rotating Rod As a conical pendulum

Consider A Rigid Rod hinged at its top point Whirled around in a circle (similar to a conical pendulum). It is given that the angular velocity (and thus the semi-vertical angle) is constant. I am ...
2 votes
2 answers
686 views

Torque on rolling cylinder

Consider a rod with two equal forces acting parallel to the direction of velocity of a rolling rod, one at each end. When analysing problems involving torque, the choice of axis should not matter. ...
1 vote
3 answers
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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 ...
1 vote
2 answers
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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
1 vote
1 answer
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Righting moment for object submerged in water

I am looking to determine the lateral angle at which an underwater camera system will no longer right itself. When on the ocean floor it is $-24.30~\text{kg}$ buoyant with the difference between its ...
3 votes
2 answers
134 views

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 ...
0 votes
2 answers
155 views

How much torque needs to be applied?

I'm using a physics programming library named Bullet and the documentation is really lacking so I have to figure much of it out as I go. I have a box with side lengths of 1 and mass 1. The "local ...
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2 answers
43 views

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 ...
0 votes
1 answer
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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 ...
0 votes
2 answers
191 views

Determining the minimum amount of torque to make wheels start rolling

Context: I am building a cart with mass m (including the cart and the payload) that has 4 wheels. The 2 back wheels will be driven by motors. I am trying to determine the minimum amount of torque ...
1 vote
5 answers
2k views

How torque about every point on Axis is same?

I read somewhere that torque about every point on an axis is same. But I am really confused about how this can be. Please help me and give an satisfactory answer
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1 answer
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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 ...
0 votes
0 answers
34 views

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
1 answer
302 views

Finding the state space representation of a dynamic model with the force and angle as control inputs vector

I am trying to design a controller to control the angle of the force on my mobile rigid body. I some questions: I am not sure how to write the state space representation with the force, $F$ and angle,...
0 votes
1 answer
591 views

Shear stress of a suspended sphere in a viscoelastic fluid

What I am trying to solve right now is that I have a magnetic particle (nanoparticle to be exact) floating in liquid that is viscoelastic and apply sinusoidal magnetic field. The applied magnetic ...
1 vote
0 answers
29 views

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 ...
1 vote
2 answers
62 views

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 ...
2 votes
4 answers
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Static equilibrium question: Horizontal rod attached to a wall

I'm doing a problem on static equilibrium and I'm unclear whether a force exists or not. This is my force diagram: The setup is: a homogenous rod with a certain mass is attached to a vertical wall on ...
1 vote
2 answers
2k views

Influence of couple-moment's position on bending moment diagram

The moment of two equally opposing force would create a couple-moment. Since the couple-moment value is invariant to the point considered to calculate the couple-moment, I can replace the two equally ...
0 votes
2 answers
4k views

Taking moment about a point

Let's say I have the following diagram: Since it's a fixed beam, I know that there will be three components acting on point A: 1) Force acting in x direction 2) Force acting in y direction 3) ...
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2 answers
3k views

Moment of force about a point definition [duplicate]

In defining the moment of a force about a point as "the tendency of one or more applied forces to rotate an object about an axis [going through a point, hence also about a point]", I see it logical to ...
0 votes
2 answers
57 views

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 ...
3 votes
2 answers
453 views

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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4 answers
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How do we interpret pulleys with mass in pulley problems?

The way I think about it, since the pulley have mass, they are a bit harder to turn? I see it as if it is friction and it increases the work required to make it move. For example, for a block with <...
0 votes
0 answers
22 views

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 ...
1 vote
3 answers
200 views

Conceptual question about wheels

I am trying to understand quite naively wheels in a specific framework. Intro We normally think of squares and circles as different concepts of shapes, but I am reframing it that both are polygons ...
1 vote
1 answer
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The torque in Euler's equations for rigid body rotations

In Taylor's Classical Mechanics, it is said that the equations are generally difficult to use because the components $M_1,M_2$ and $M_3$ of the applied torque as seen in the rotating body frame are ...
0 votes
1 answer
153 views

Assistance in Francis Turbine Lab Experiment

Lately I did Francis Turbine Experiment at my institute. The objective was to find the efficiency of the turbine. Power input was found using flow rate and pressure gauge. Power output was found by ...
0 votes
2 answers
85 views

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.
15 votes
3 answers
1k views

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 ...
0 votes
4 answers
714 views

Acceleration of the centre of mass of a rod

The acceleration a of the center of mass of a system is equal to F/M, where F is the net external force and M is the total mass of all the particles of the system, or at least that is my current ...
0 votes
1 answer
30 views

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 ...
0 votes
1 answer
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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 ...
0 votes
3 answers
652 views

Torque and Angular Momentum Relation?

Suppose we have a tyre hanging in mid air and has a metal rod in the middle of the tyre. If we apply a force at the end of the tyre then a Torque will be produced. I heard from someone that if we ...
-1 votes
2 answers
54 views

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 $r<R$. ...
1 vote
2 answers
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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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1 answer
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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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3 answers
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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. ...
2 votes
0 answers
34 views

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
5 answers
89 views

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 ...
0 votes
2 answers
125 views

Physics of pushing the top of a box a little bit to make it rock back and forth

Context: I'm trying to make a simulation of a box that you can apply force to the top and it will oscillate back and forth until the energy in the system reaches equilibrium again. Visual ...

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