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Questions tagged [rigid-body-dynamics]

The study of the movements of a collection of connected bodies subject to external forces in the absence of deformation. This tag should be used for questions on the analysis of 2D/3D dynamics of rigid bodies, do NOT use this tag because your question contains a rigid structure.

Rigid-body dynamics is the study of the movements of a collection of connected bodies subject to external forces in the absence of deformation. The assumption of a rigid body (no deformation) allows the dynamics to be described by translations and rotations, with the Euler angles often playing an important role in the analysis.

Typically, questions about rigid-body dynamics involve either a single solid object rotating about an arbitrary axis or a set of solid objects moving due to an external force.

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Why does a bowling ball hook in the shape of a parabola?

As an aspiring professional bowler, I'm attempting to understand all the factors that influence a bowling ball motion. The simplest case is when the bowling ball is a uniform sphere and the center of mass is at the geometric center of the ball. (As…
Jon Doe
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Torque on puck moving on plane without friction

We have two pucks moving on a plane without friction. On one of them a force is applied on it's center of mass. On the second a force of equal magnitude is acting tangential to the puck and at a distance equal to it's radius. Which one will be…
eliasp67
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Dynamics equations for unbalanced wheel rolling without slipping on flat surface

I would like to develop a system of differential equations describing dynamics of an unbalanced wheel rolling without slipping on a flat surface. The difficulty i'm running into is that there is no steady state, like, for example, in the case of a…
Daniel Genin
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Time Evolution of a Rigid Body

I've been very confused about how we get the derivation for the time evolution of a rigid body, in the resources I've seen it's given by $$\dfrac{d\vec r_{\text{rotating frame}}}{dt} = \omega \times \vec r_{\text{rotating frame}}.$$ While going…
Diego Vera
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Does angular acceleration depend on the reference point?

Assume that we have a free rigid body, its own weight being the only force acting on it. If I want to know its angular acceleration, then I calculate the total moment acting on the body. Now, if I choose to compute the moment wrt the center of mass,…
Javi
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Pure rolling as pure rotation

When an object is in pure rolling motion its kinetic energy is equal to $\frac{1}{2}mv^2+\frac{1}{2} I \omega^2$ where $I$ is moment of inertia through centre of mass and $\omega$ is angular velocity about centre of mass. But it's KE is can also be…
Anonymous
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Why does a rigid body rotates about it's centre of mass?

When an impulsive force is acted upon a rigid body, (and the force doesn't pass through the centre of mass) why does the body rotates specifically about an axis passing through centre of mass ?
user95878
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What causing the axis of rotation of a bowling ball to change

A bowler throw a bowling ball with an initial velocity and initial rotation. Let the initial velocity vector be parallel to the y-axis. Now, the ball is rotating about an axis, call that the axis of rotation. This axis will form 2 angles from the…
Jon Doe
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Contact between two rigid bodies. How does contact force is distributed in the contact surface?

We have a rigid body with some scalar function of vector argument, which describe density of body at concrete point in space. The body lie on the table in the stable state, elements of it doesn't perform any movement. The body is situated on the…
Konstantin Burlachenko
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What will happen if I remove a nail which stops a plank from moving on a smooth floor because of a solid sphere pure rolling on it?

What will happen if I remove a nail which stops a plank from moving on a smooth floor because of a solid sphere pure rolling on it?The plank has it's upper surface which is in contact with the sphere rough, therefore the sphere is rolling(purely). I…
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Rigid body translation and the moment about a point

ok the statement of the moments , beside the fourth car image How there is a moment about the point A although there is only translational motion , is not the car only moving and not rotating ? why we do not say that 5 W = 12 NB
Mohamed Osama
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The horizontal components of velocities of two points in a rigid body must be equal but can we conclude that vertical velocities have to be equal?

Consider two points in a rigid body and their velocities at a particular angle to the horizontal. The horizontal components of velocities must be equal so as to satisfy the basic definition of a rigid body. Can we also say that their vertical…
Anvi Mahajan
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Off center, perpendicular force applied to rigid body with pivot/ fulcrum at center of mass?

I feel like this question has been asked in so many ways, but I am still unable to explain my personal experience based on previous answers. From other discussions: You can always replace an off-center force by the same force centered plus a…
JohnC
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How a stick in space moves when force only acts on one end? (suppose stick is rigid body)

I am confused with how to put inertia in to this problem, which suggests the end the force acts on should move first while another end remains fixed at first moment. I think that the stick should sway forward and backward with central of mass moves…
Shiny
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For a rigid body in equilibrium (both translational & rotational), is the net torque about any axis of rotation zero?

Is the net torque about any point zero for a body in equilibrium? Or the net torque only about the centre of mass zero?
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