Class 7 relative motion and fixed axis rotation

Alsotrueforcurvilineartranslation y rb y y rb ra rb

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Unformatted text preview: rA rB / A x’ rA x’ Translation Note, all points in a rigid body subjected to translation move with the same velocity and acceleration. Also true for curvilinear translation y’ rB y’ y rB rA rB / A rA x’ x rB / A rB x’ y’ rB / A x’ rA Not true for rotation about a fixed axis rB / A rB / A Dyn am i by cs Hib bele r y’ rB y x’ rB / A rA rB x rB / A rB rB / A rB / A Or general plane motion y’ y’ y’ y’ B rB / A rB y A rA x rA rB / A rB / A rB rA x’ x’ rB rA x’ A rB x’ rB / A B New Terminology • • Theta (θ) is an angle (radians) Omega (ω) is the angular velocity (rad/s). It is the time derivative of theta (θ) & and there is only one per rigid body. , θ =ω • • && acceleration (rad/s2). It is the time θ =ω Alpha (α) is the angular & = α derivative of omega (ω), and there is only one per rigid body. In planar motion, translation occurs within the reference plane Rotation Vectors • Right-hand rule: if you curl your fingers in the direction of the rotation, your thumb points in the vector direction Cross­product shortcut •...
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