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 May 1 comment Finding $\theta$ at any point in time Use the equations of motion with the following quantities: \begin{align} \sum \vec{F} & = \begin{pmatrix} F_x \\ F_y \\ 0 \end{pmatrix} & \sum \vec{M}_A & = \begin{pmatrix} 0 \\ 0 \\ \tau \end{pmatrix} \\ \vec{a}_A & = \begin{pmatrix} \ddot{x} \\ 0 \\ 0 \end{pmatrix} & \vec{\alpha} & = \begin{pmatrix} 0 \\ 0 \\ \ddot{\theta} \end{pmatrix} \\ \vec{c} & = \begin{pmatrix} \ell \sin\theta \\ -\ell \cos\theta \\ 0 \end{pmatrix} & \vec{\omega} & = \begin{pmatrix}0 \\ 0 \\ \dot{\omega} \end{pmatrix} \\ I_C & = \begin{vmatrix} & & 0 \\ & & 0 \\ 0 & 0 & I_{zz} \end{vmatrix} \end{align} Apr 30 answered Momentum of a rack and pinion gear system excited by a time variant force Apr 30 comment Spring pendulum system Welcome to Physics. What is your question? Apr 29 comment Rotation of a vector The direction of $(1,2,3)$ is the same as the direction of $(2,4,6)$ where all the components are scaled by 2. Apr 29 answered Rotation of a vector Apr 29 comment Rotation of a vector Not if the components are all scaled by the same amount. The component change but the direction is does not. Apr 29 answered Net force equal to mass multiplied by acceleration of centre of mass Apr 29 answered Rigid Body Dynamics - Calculating Rotation of an Object Apr 29 comment Newton's 2nd law for rotation (accelerated rolling and inertial frame of reference) This question has been answered before in here multiple times. It is hard to find past questions unless you use the right keywords. Apr 29 comment Newton's 2nd law for rotation (accelerated rolling and inertial frame of reference) Possible duplicate of Why is the center of mass frame always used in rigid body dynamics? Apr 28 answered What is the physical meaning of reduced mass? Apr 27 comment Can't identify static and kinetic friction regions Are you pulling or pushing on the specimens ?? Apr 27 comment Can't identify static and kinetic friction regions To set the part in motion at an infinitesimal time you are looking at a frictional impulse being applied. I doubt you can measure this. Apr 27 comment Can't identify static and kinetic friction regions Because parts are not rigid it is possible the movement gets initiated by a strain wave along the material. For steel this wave travels at 5000 m/s and so if you have a 1m long specimen the time to unstick is in the order of 1/5000-th of a second. So yes, it is entirely reasonable you are missing it. Apr 27 comment Can't identify static and kinetic friction regions How are you measuring friction? Static friction may occur over such small time period that you might not see it. Apr 27 comment Rotational Dynamics Question What is your question? This appears to be a question someone asked of you to answer. Apr 26 comment How to calculate torque required? Do you know the mass moment of inertia of the pulley, motor and any gear-train attached to it? The dynamics of the system might depend on this a lot. Apr 26 comment How to calculate torque required? This answer would be much better with math formatting. Enclose expressions in dollar signs$...$ for inline or $$...$$ for paragraph style. Then use \frac{a}{b} for fractions like $\frac{a}{b}$. Apr 26 answered When only part of the surface an object is in contact with has friction, what is the normal force I should use? Apr 25 comment Why is the Plane progressive wave equation $y= a\sin (kx-wt)$ for positive direction of x-axis? Find for which $x$ the argument $kx-\omega t$ is zero? It will be $x = \text{(positive)} \,t$