Lecture_25_2007

# Lecture_25_2007 - Centre of mass/gravity in a nutshell 1 1...

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Unformatted text preview: Centre of mass/gravity in a nutshell 1 1 n i i i c m n i i m x x m = = = ∑ ∑ For solid objects use symmetry to help find C of M Sometimes treat holes as negative mass objects Simplify problems by reducing to simple shapes For isolated objects centre of mass is fixed If the C of M is expressed relative to a moving coordinate system be very careful when finding the absolute positions of parts of the system (relate back to fixed points such as the centre of mass or a fixed object in the environment) For moving objects and collisions where no external force is applied the centre of mass will continue in a straight line with constant velocity (Newton 1) Rotational Motion The Tumble dryer Alice Through θ ∆ x ∆ t θ ϖ ∆ = ∆ x t υ ∆ = ∆ [ ] m [ ] rad [ ] / m s [ ] / rad s t ϖ α ∆ = ∆ a t υ ∆ = ∆ 2 / m s 2 / rad s F Fl τ = Linear world Rotational world +ve +ve [ ] N [ ] Nm W F x = ∆ [ ] J W τ θ = ∆ [ ] J θ ∆ Kinematic equations...
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## This note was uploaded on 04/07/2012 for the course PHYS 111 taught by Professor Dr.jackman during the Fall '07 term at Waterloo.

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Lecture_25_2007 - Centre of mass/gravity in a nutshell 1 1...

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