83.1 Position and displacement of a particle Note Ar is independent of thethe specifi coordinate system we choose 3 The position of a moving particle is a function of time r(t)=x(t)i □■■■ ④ the path of the particle is a straight line t A graph ofx versus t 83.2 The speed and velocity of a moving particle 1. Average speed and average velocity Ar Define: aveRt ave t 个:d≠EF v≠v 2. Instantaneous velocity H and instantaneous speed (t)=x(t) x(2 x(o r(t+A)=x(t+∠)i3 Note: 3 The position of a moving particle is a function of time, r r 2 ∆ is independent of the the specific coordinate system we choose. r t x t i ˆ ( ) = ( ) r x t A graph of x versus t §3.1 Position and displacement of a particle 4the path of the particle is a straight line. 2. Instantaneous velocity and instantaneous speed §3.2 The speed and velocity of a moving particle 1. Average speed and average velocity Define: t s v ∆ ∆ ave = t r v ∆ ∆ r r ave = ave ave s r v v r r Q∆ ≠ ∆ ∴ ≠ t x 1 ∆t 2 ∆t x(t) ( )1 x t ( ) 2 x t r r t x t i i ˆ = ( ) = ( ) r r r r t t x t t i f ˆ = ( +∆ ) = ( +∆ ) r r