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 Apr 22 comment Tension and friction. Cool question You might want to mention that contact forces act in equal and opposite fashion on contacting bodies. Apr 22 comment May a point rotate about itself? Please accept whichever answer was most helpful to you. Apr 22 comment May a point rotate about itself? @lucas, Why? Why do points need rotations. To have rotation you need a definition of an orientation. What is the orientation of a point? Also, a location plus orientation is already called a coordinate frame. Apr 21 comment May a point rotate about itself? $0·\infty$ can be anything. Usually we know $v$ and $\omega$ and we calculate $r$. If $\omega=0$ then $r=\infty$. Apr 21 comment May a point rotate about itself? You understand the linear velocities are a vector field. They change value as a function of position. So only at the central axis the value matches between the two cases. Apr 21 comment Friction of a scissor The coefficient of friction is a material property and does not change with geometry. The amount of frictional force changes. Is that what you are asking about? Apr 21 reviewed Approve Friction of a scissor Apr 21 answered May a point rotate about itself? Apr 21 comment Rolling without slipping taking the contact point as pivot Think of the friction force as a function of slip velocity. When slipping is zero friction is zero, otherwise friction acts in a way to minimize slipping. Apr 21 comment Question about Thrust; am I correct? The above is an application of the product rule we learned in calculus. Apr 21 answered “Sweet Spot” of Rod-Pendulum - Problem Clarification Apr 21 answered Why does the angular speed formula end up in radians per second? Apr 21 comment Why does the angular speed formula end up in radians per second? can u show us your calculation? Apr 20 comment What is the minimal G-force curve in 2-dimensional space? No it is a conceptual proof. Having (flat) constant lateral acceleration is better than any curve which is limited in its maximum value. It is like the area under a curve is always smaller than the area of a rectangle encompassing the curve. Apr 20 comment Rotation of rigid body with two different angular velocities Equation on a non-inertial frame do not make sense. I always look at things on inertial frames, just at different locations or with different modeling choices (absolute vs. relative motion). Apr 20 revised What is the minimal G-force curve in 2-dimensional space? added 1787 characters in body Apr 20 answered What is the minimal G-force curve in 2-dimensional space? Apr 20 comment What is the minimal G-force curve in 2-dimensional space? Possible duplicate of non-accepted answer physics.stackexchange.com/a/185261/392 Apr 20 answered Rotation of rigid body with two different angular velocities Apr 20 comment Rotation of rigid body with two different angular velocities Is $\omega$ the joint velocity (relative) or the absolute velocity of the cylinder?