Lec03_Sum_f

# Lec03_Sum_f - Summary Lecture 3 There are four types of...

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1 Lecture 3 Vectors Two Dimensional Motion Relative Motion Physics 111, Summer 2011, June 15, Lecture 3 Summary There are four types of motion: horizontal , vertica l, circular , two dimensional , and projectile . Acceleration tells us how quickly the velocity changes: the change in velocity divided by the change in time: t v a Δ Δ = / gy y g Acceleration from the rest ( a = const): at v = at v 2 1 = 2 2 1 at x = Acceleration during the motion ( a = const): at v v + = 0 2 0 at v v + = 2 0 2 1 at t v x + = If the air resistance can be ignored, any object falls down with a constant downward acceleration of g = 9.8 m/s 2 regardless of its mass and composition. 2 Some equations for vertical motion ( g = const): gt v v + = 0 2 0 0 2 1 gt t v y y + + = Physics 111, Summer 2011, June 15, Lecture 3 A scalar is a quantity which has the magnitude only: mass, length, time, volume, temperature, etc . Scalars and Vectors vector is a quantity which has the magnitude and direction : (Magnitude of ) A A In physics we need vectors because the real world is at least three dimensional . displacement, velocity, force, etc . A A = = 3 A B A B A B A + , , Physics 111, Summer 2011, June 15, Lecture 3 How we can show a vector, indicating, for example, the velocity of 30 m/s at 30 0 to north-east? Vectors: Magnitude and Direction 0 0 1. Magnitude: choose a scale: 2. Direction: show the angle of 30 0 to + x -axis: s m v / 10 = s m v / 30 = ) ( north y + 4 0 30 = θ A ) ( south y ) ( west x ) ( east x + ) 30 , / 30 ( 0 s m A 0 Physics 111, Summer 2011, June 15, Lecture 3

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2 Working with Vectors (#1) 1. Addition 2. Subtraction
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Lec03_Sum_f - Summary Lecture 3 There are four types of...

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