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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How can one calculate the torque around this point?

I'll link to one of my previous problems, since the setup is very much alike this one for the problem I'll be solving: What happens with the pendulum when we choose this angular velocity for a ...
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Angular Momentum of asymmetric physical pendulum (Rigid Body)

The angular momentum of a rigid body respect to a pole $O$ located on its axis of rotation $z$ is uniquely determined if we know its angular velocity: $\vec{L}_O = I_z\vec{\omega} - \omega\iiint_V ...
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How the object rotates?

Why the object actually rotates ? When I researched about this topic , I have gotten satisfying answer from here: Why do object rotate at all? All the atoms and molecules of the object are connected ...
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Gear Ratio And Torque Relationship

suppose a gear teeth ratio of (1:10) >> then it is obvious that the smaller gear will be faster than the larger gear >> And the higher gear has more torque which means a higher ...
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How are the tipical values of the Columbus and viscous friction torque?

I am mathematically modeling a motor and I want to calculate the constant columbus and viscous friction torques. The forumula I found was: where a is the voscous friction torque and b is the ...
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For rotational equilibrium of a rigid object, about which point does the torque of the body have to be zero?

In the definition of rotational equilibrium for a rigid body, the net torque about a point has to be zero. Now, about which point will the torque be calculated? Will it be the centre of mass or centre ...
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Calculating the moment/torque of a force applied over an area [closed]

This diagram shows a current carrying wire (from PQ) and a uniform magnetic field applied across the wire (from 85-90 cm) into the page, therefore the force is upward. How would one calculate the ...
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Can we say torque at each point is same [closed]

So here to find force exerted at point c is F'y=Fx as torque at each point is same right?
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A dilemma regarding torque when a body moves in circular motion

Consider a mass 'm' tied to a rope and I am rotating it in a circular path with constant angular speed.One component of the tension balances the weight and the other component provides centripetal ...
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When two systems of forces acting on a rigid body are equivalent?

My book says that "it is clear that if you replace the system of forces with a second system having the same resulting force and the same resulting moment, with the same initial conditions the ...
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What rotates a disk hung at center of mass when it is tilted?

when a disk is hung by a string attached to the center of mass point is tilted, what is making it fall and become horizontal again Note the white line is a light string. Here $Torque_{net} = 0$ and $...
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This question is about motor power requirements

If I have a motor that has a power of 20 kilowatts, does that mean that the motor can produce a torque of 10k newtonmeters at 2 rpm, or analogously a torque of 2 newtonmeters at 10k rpm since the ...
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Why is torque defined as $\vec{r} \times F$?

Here I cannot convince myself myself that it is units because the torque is defined to be in units of Newton meter is a reiteration of the law stated above. Why was it not $r^2 \times F$ or $r^3 \...
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1 answer
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Why is the sum of torques for each particle equal to the external torque?

Let's assume we have a rigid body. The internal forces all have equal and opposite counterparts so the they will produce a net zero torque. We can therefore ignore internal forces when calculating the ...
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What happens with the pendulum when we choose this angular velocity for a rotating platform?

The problem is presented below: I've managed to find the angular frequency of the pendulum using torque, and small-angle approximation. Finally, I wanted to check my expression and see whether it's ...
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Kinetic Friction from torque of sliding ball

I'm having some trouble finding an answer to this question which is strange because it's very simple. Perhaps I'm not thinking about it properly. Imagine you have a mass with a hole running through it ...
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Why do internal torques cancel?

I don't understand why torques produced by internal forces cancel in the sum $\sum \tau$. My textbook gives the following explanation: due to N3L, if a particle exerts a force on another particle of ...
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Deriving torque and rotation without an ideal rigid body

Let's say that we have two masses that are connected by a massless rigid rod. I'm assuming there are no external forces acting on the system. If we were to apply a force where the force over time is ...
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Deriving spherical pendulum equations with an Applied torque

I'm and electrical engineer and I'm trying to derive a state space model for a spherical pendulum with an applied torque to the system, not energy. So if I understand correctly I can't apply the ...
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What is the physics behind a TV wall mount? [closed]

As I was installing this wall mount, I began to wonder how exactly physics is at work with it. In other words, how does the design of the mount play a role in ensuring that the mount itself supports ...
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2 answers
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Does this body tilt if we push it with F force?

The question exactly is: A $20 \text{ kg}$ uniform density wooden crate of height $2 \text{ m}$ and width $1 \text{ m}$ is pushed at one of its edges at its top by a $25 \text{ N}$ force as shown in ...
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-1 votes
2 answers
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What the are forces acting on a wheel of a moving bicycle?

For the wheel of moving bicycle or bike why is net torque $0$ i.e $\tau_{\text{NET}}=0$? If it can be shown that the wheel is in translational equilibrium i.e. $\sum_{}^{}\vec{F}=0$ then it's also in ...
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Moment of inertia when velocity is zero

The most basic form of the moment of inertia comes from fix axis rotation, that is $$L=\int rv\, dm=\int(r\omega)(r\,dm)=\omega \int r^2\, dm\tag{1}$$ Here $r$ is the perpendicular distance from the ...
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Doubt on the application of conservation of angular momentum

The following is the picture from the you tube channel physics desmos. In this the man is demonstrating the conservation of angular momentum. Now the explanation of it is also given in my book as ...
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Why is net torque zero in this case?

As an application of conservation of angular momentum around a fixed axis the following example was given in our textbook. If a girl sitting on a swivel chair starts rotating with her arms streched as ...
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Torque due to external forces only

Suppose two parallel lines L1 and L2 at a separation of 100 metre . Suppose two charged particles are moving with constant and equal speeds , the first one on L1 and other on L2 ; and their direction ...
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2 answers
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Simple pendulum using plane polar coordinates: where did I miss a minus sign? [closed]

Suppose we want to write the equation of a simple pendulum using plane polar $(r,\theta)$ coordinates with the point of suspension as the origin and with $\theta$ increasing anticlockwise from the ...
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3 answers
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Will an object undergoing translation move faster than if it underwent both translation and rotation?

So I'm revisiting my physics, as I'm looking to solidify my foundations. I was going over the chapters concerning rotation of rigid bodies and I just thought of this problem: If an impulse is applied ...
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An exercise about angular momentum in "The Mechanical Universe" (Frautschi)

I'm reading through "The Mechanical Universe" and I'm stuck with one exercise in the chapter about angular momentum. It goes like this: A particle of mass $m$ is at the end of a rod of ...
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Angular momentum on a rotating wheel

Let's consider a wheel extended with its axle on both sides. Tie a string at both ends of axle. Note that we should keep the wheel vertical. Upon leaving one string the wheel will tilt. Now keeping ...
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Can anyone guide me on torque equation to rotate a part?

hope you all are doing good. I am a bit confused on which equation to use to calculate the torque required to rotate a part. I want to use a hydraulic motor at the 6th axis (end of robot arm) of ...
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Difference between Torque and Speed

Torque is the twisting force acting on a body while speed is revolution per minutes or seconds. If I apply a twisting force on a ball with my hand ball will rotate. If I increase this twisting force ...
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Will the bar rotate about the center of mass or not?

Here, $O$ is the center of mass of the unconstrained rigid bar: none of the points, including $O$, are affixed. According to Salman Khan, due to $\vec{F}$ the bar will start to rotate about $O$. ...
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Can torque be taken about any axis of a stick?

Here, $O$ is the center of mass of the uniform and rigid bar. $O$ is not affixed. In fact, none of the points on the bar are affixed. Now, a force $\vec{F}$ acts at $B$. There's no doubt that the ...
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Calculating lifting force with disc magnet

Let's say I have a flat metal sheet lying on the floor and I want to lift it straight up with a disc magnet. The magnet cannot tilt, which means that the sheet must stay in a horizontal position ...
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Source of torque for rotational Imbalance

This figure was used as an example of rotational imbalance in my physics textbook. In this case, equal masses A and B attached to a rigid and massless rod rotate counter-clockwise in the x-y plane (...
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Resource recommendation for rigid body dynamics [duplicate]

I want a book at undergrad level that teaches rigid body dynamics from a physical perspective, that is explaining the need for each term introduced, instead of saying "this is a term which is ...
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Why center of mass constant is zero?

The Center of mass frame (CM) is defined in such a way that total momentum in this frame is zero. Thus $\vec P'=\sum (m_i\vec v_i')=\sum \big[m_i(\vec v_i-\vec u)\big] =\vec P - M\vec u=0 \tag{1} $ ...
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1 answer
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How can a bicycle wheel built with concurrent spokes be solid?

Consider the fixed point at the top of Figure A. That point is connected by a strong but thin metal rod—one acting like a rope—to the hinged point at the bottom of the figure. When we apply a ...
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Splitting moment of force (MOF) about vertical axis though centre of mass (COM) into Components About Centre Of Pressure (COP)

I have been trying to understand whether the below is correct or not. The individual moments of force (MOF) about a vertical axis passing through the COM (Centre Of Mass CM). Is equal to the below ...
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Distribution of contact forces on a square at rest

Consider a square (blue) on top of a platform (yellow), on which gravitational force (black) acts. We know that if the blue square is in equilibrium, contact forces from the platform (white) must act ...
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Torque on a rod in a harmonic potential

I'm trying to find an expression for the force and torque on a rod in 2D subject to an external harmonic potential \begin{equation} V = \frac{k}{2}x^2 \end{equation} I know that the force on the ...
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What is the maximum force that an average bicycle chain sprocket can withstand?

I want to use bicycle chain sprockets for a non-bicycle related project and I'm trying to figure out what is the maximum torque I can apply. I did a quick calculation taking a real life example - I ...
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Question regarding $ΣM= Iα$ and an example problem given by my professor

In this example problem, an applied moment and two hanging masses of different values and in different positions caused a double pulley to rotate and angularly accelerate. As you can see, on the ...
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4 votes
3 answers
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How are force couples free vectors?

According to wiki, In rigid body mechanics, force couples are free vectors, meaning their effects on a body are independent of the point of application. I'm having some trouble understanding this ...
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4 answers
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If two unlike forces act on two different points of a rigid body, won't the body just start to rotate?

Question: Two unlike parallel forces $P$ and $Q$ $(P>Q)$ act at $A$ and $B$ respectively. If P and Q are both increased by R, show that the resultant will move through a distance $d=\frac{R}{P-Q}$. ...
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2 votes
2 answers
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Relationship between net force and net torque

Why are the following two statements false? If net torque is zero then net force must be non-zero. If net torque is non-zero then net force must also be non-zero.
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What is positive rotation direction of a pulley in the Atwood machine?

In the Atwood machine the mass $m_1$ hangs on the left and $m_2$ hangs on the right, with $m_2 > m_1$. When released from rest the system accelerates clockwise which we define to be the positive ...
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Why is the propeller torque, which is cancelled by drag, considered in calculation of net torque about the rotation axis?

I am calculating the net torques and forces about the yaw axis of a quadrotor. If $I$ is the moment of inertia about the rotation axis, and $\omega$ is the angular velocity of the propeller, then the ...
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The shell theorem and net torque

Consider the setup shown in the picture. A spherical uniform density mass of $m_1$ is connected to a ball-and-joint socket via a bar of negligible mass. Another spherical uniform density mass $m_2$ ...
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