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Unformatted text preview: Lecture 19 pls-19.1 Rotational Kinematics I Media: 1. Tennis ball, foam with dot, hammer 1. Rotational Kinematics Goal is to describe the rotational motion of an object about a an axis of rotation that is fixed (with respect to the object). If the object is freely rotating, this axis passes through the center of mass. Demo: Tennis ball, foam with dot, hammer To do this we use angular variables that are completely analogous to 1D kinematic variables: variable linear motion rotational motion position x θ displacement i f x x x − = ∆ i f θ θ θ − = ∆ velocity t x v x ∆ ∆ = dt dx v x = t ∆ ∆ = θ ω dt d θ ω = acceleration t v a x x ∆ ∆ = dt dv a x x = t ∆ ∆ = ω α dt d ω α = Lecture 19 pls-19.2 2. Angular Position θ and Displacement θ ∆ In general, when discussing angular kinematics, we use radians rather than degrees to express angles. A radian is defined as arc length s divided by radial distance r , r s = θ radians (rad)....
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- Fall '11