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Unformatted text preview: equal that of all particles Physics 1001 Notes External Forces and the centre of mass • Only external forces change the centre of motion • Therefore the system behaves like one big mass at rCoM • External forces appear to act through the CoM 12 Physics 1001 Notes Chapter 9: ROTATION OF RIGID BODIES Rotational Motion • • Rigid body rotation is described using; o Angular displacement Ø in radians o Arc length s=r Ø around a circle of radius r o R is the perpendicular distance to the rotation axis Angular velocity is the change in Ø with time o • (radians) o This is instantaneous angular velocity, not average angular velocity o Direction is given by right hand rule on z axis - vector Tangential velocity o • dθ dθ w= v= ds dθ =r = rw dt dt Angular Acceleration o αz = dw z dt (Radians/s2) o Magnitude is α z and direction is along axis o Same direction as w if speeding up o Opposite if slowing down Rotational Kinematics for α = constant • For α =constant; analogous to 1- D linear motion Physics 1001 Notes Relating Linear and Angular Kinematics • Two components of linea...
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This note was uploaded on 04/09/2014 for the course PHYS 1001 taught by Professor Helenjohnston during the Three '13 term at University of Sydney.

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